1 illegal gun. 12 weeks. A dozen criminal acts.

WASHHINGTON - The Glock 17 rested in a display case in a gun shop in a Virginia strip mall.

Black. Easy to shoot, easy to handle. A used 9mm. For $325 in cash, it was sold to a man who swore in writing on a federal form that the gun was for him.

It wasn't.

Within days he'd pass the semiautomatic to a friend who had driven him to the store. That friend passed it to others.

Six days after the Glock was purchased on Aug. 4, 2014, it was used in a gun battle that wounded six at a birthday barbecue a few blocks from Nationals Park in Washington.

It was fired three days later at a woman driving along a District of Columbia highway listening to R&B, a victim who happened to be an off-duty D.C. police officer headed home from a nightclub. She kicked off her Louboutin heels and punched the gas pedal trying to catch the shooters.

The same night and less than two miles away, the Glock was fired again at a man stopped at a traffic light in a hulking Yukon Denali. In a coincidence, he, too, was a cop and a random target, in plain clothes and driving into the District to testify in a murder trial.

Shot four times, desperately trying to get to his service weapon in a gym bag on his front seat, the officer rammed his SUV into the shooter's car to try to force it to stop.

The officer never managed to fire a round, and the gunman with the Glock got away.

The Glock 17 was brought to the nation's capital in 2014, one of 2,178 illegal guns taken off the streets that year by police in the District. Since then, nearly 5,000 more guns have been seized in raids and found during arrests and at crime scenes.

The path of the Glock was tracked through court files, interviews, photos, surveillance videos and a 911 call. To follow the saga is to understand the devastation and suffering that just one gun can cause.

It changed hands at a rapid pace and traveled across state lines - stashed in houses, a glove compartment and a flower pot before being tossed under a car in a panicked sprint from police.

The Glock was shared in just three months by the two men who started its trafficking at the strip mall and at least five more people who knew how to get to the gun when they needed it and how to pass it off when they didn't.

The speed at which guns move from sale to use in a crime is breathtaking, and the Glock's story demonstrates why law enforcement officials say they often are playing catch-up to the firearms in urban areas. And as the Trump administration and others draw attention to violence in cities, big city mayors and police chiefs point to the easy availability of illegal guns as a driving factor.

Guns in high-crime areas "are not disposable commodities" and tend to stay within a group even after they've been used in crimes, said Daniel J. Board, who runs the Baltimore field office of the Bureau of Alcohol, Tobacco, Firearms and Explosives.

In recent years, investigators in the District have uncovered what they dub community guns hidden under a refrigerator at a drug stash house and beneath the front stoop of a home.

But the ever-more-rapid pace from purchase to street use is ominous even to experts who have tracked firearms for years.

The span between when a gun is sold and its use in a crime in the District has shortened every year since 2010, ATF tracking shows, and the number of guns showing up in crimes within three months of their sale has doubled over the past five years.

"The bottom line," Board said, "is that when we see those short time to crime spans, our immediate thought" is the link to violent crime.

The Glock 17 was part of a summer 2014 buying spree.

In the span of a month, Jamal Fletcher Baker and his buddy, Lawrence Monte Morgan, visited five Virginia gun dealers, spending more than $3,500 on a dozen firearms, court files show.

Sometimes they bought two at a time. Sometimes they doubled back to a store within days.

A Smith & Wesson pistol in Richmond. A Walther Uzi and a Ruger P345 in Ashland.

And at the Manassas store, the Glock.

Baker and Morgan weren't experienced street hustlers when they teamed up in the gun scheme that authorities said included posting weapons for sale on Instagram.

Morgan grew up in violent neighborhoods in Maryland and the District. He had no job, was a new father and at the age of 24 was a rapper known as "Stunna."

Baker was raised in a strict military family in Prince George's County, Maryland. He was 23 and selling shoes on the street.

The two had met a few years earlier while trying to break into the music industry.

Together, a court case would show, they went to Virginia Arms Co., about 50 miles from the District, on a late afternoon in early August and from a display, chose the Austrian-made 9mm Glock 17.

Baker filled out the required paperwork, Federal Form 4473, and declared he was buying the gun for himself - a lie that is a felony. He quickly gave the Glock to Morgan, the intended owner.

In less than a week, the Glock was used in a firefight.

A birthday party was still going strong just before 2 a.m. on Aug. 10, 2014, at the family home of Romeo and Ronald Hayes in Southwest D.C. within blocks of Nationals Park, the baseball stadium.

At the back of the brick townhouse on N Street, about a dozen people were at the cookout when a pair of gunmen rolled up in a car on a side street. They jumped out and fired at least 15 rounds. Partiers dove behind sheds and trash cans as the gunmen barged through the yard and toward the house.

A friend of the Hayeses rushed inside, and according to a police affidavit, grabbed a gun he'd recently bought from Morgan. The Glock 17 by then had been tricked out with an extended magazine that held 30 bullets.

The friend passed the gun to Ronald Hayes to return fire against the shooters, who had strafed the party in an apparent feud with one of the guests, police would say later in court filings. He missed.

Six partygoers were wounded, one shot in the neck, stomach, leg and foot. Blood trailed through the kitchen and living room.

Two suspects - not the Hayeses or their friend - were arrested but charges were not pursued when the suspects, victims and partygoers refused to cooperate with detectives.

Police recovered casings from several different guns.

Three were from a 9mm that were later tracked to the Glock 17.

Later that morning, the Hayes brothers, the friend who had bought the Glock and a few others regrouped at a house in Prince George's County, Maryland, where they hung out for two days, drinking tequila and using drugs.

Sometime after midnight on Aug. 13, Romeo Hayes, then 27, and the friend decided to go clubbing at the Opera Ultra Lounge and drove in to downtown D.C.

By the time Romeo Hayes and his friend left around 2:30 a.m., he was high and irritable and got into a shouting match with men near his parked car, according to court files.

The friend got behind the wheel and they headed to Suitland Parkway to get back to Maryland. Hayes pulled the Glock 17 from the glove compartment.

Off-duty police officer Shaquinta Gaines left the club at around the same time.

A mother of two who had known she wanted to be a cop from the time she wore a safety patrol vest in elementary school, Gaines had been out for a girlfriend's birthday party, dancing in her red-soled shoes.

She had left her sidearm at home.

About six miles from the club, a staccato of dink, dink, dink sounded, interrupting the R&B music Gaines was listening to in her car. As a burgundy Nissan Altima zoomed by, Gaines realized the dinks were gunshots.

With her heels kicked off, she put her foot to the gas pedal, surging to nearly 90 mph as she tracked the Altima's taillights on the parkway.

Cresting a hill, she soon caught sight of the car in the distance locked in what looked like a monster truck battle with a big SUV on Southern Avenue at the D.C.-Maryland line.

She sped up, eventually bearing down on the Altima's bumper, and called out the license plate to a 911 operator just as Romeo Hayes leaned out the passenger side window and opened fire with the Glock 17.

"Oh my God, they shooting again," she told the dispatcher. "I don't know what the hell is going on."

Gaines ducked until the shooting stopped.

The 38-year-old by her own words was "born and bred in the violence" of the Sursum Corda neighborhood near Washington's Union Station. She'd been on the force for 12 years. But three minutes into her 911 call, her voice had a tremor.

"Is somebody coming here right now?"

- - -

From his Yukon Denali, Thurman watched a car racing toward him from the rear as he sat at a traffic light.

The D.C. detective had left his rural Maryland home before dawn in a T-shirt and sweatpants to get to his police district in Northeast and read up on a new case.

Seeing the car speeding up behind him at Southern and Pennsylvania avenues, flipped on his handheld police radio and reached for his pistol in the gym bag on the front seat.

When looked up again, the Altima had pulled up next to him. "I saw the gun staring right at me," recalled recently.

It was, investigators said, the Glock 17 in the hands of Romeo Hayes.

The first shot hit 's left forearm. It went numb.

cranked the steering wheel to the left using his right hand.

"My goal was, I'm going to stop them," he said.

He hit the gas hard, ramming the front of his SUV into the passenger side of the Altima.

Romeo Hayes fired again, driving gaping holes into 's windshield. Twelve bullets pierced the SUV, four hitting in the left shoulder, stomach and chest before the Altima pulled away.

stayed behind the car for only a few more blocks before he saw flashing police lights headed to the scene.

Dizzy, he came to a stop as officers rushed to the 27-year veteran, talking to and fighting back tears as they put pressure on his wounds and waited for the helicopter that would lift him to a trauma center.

By then, the Altima - and the Glock - were gone.

Doctors removed a bullet from 's forearm but left bullets in a shoulder and his abdomen.

A fragment too risky to remove remains near his heart.

has never asked how near. "To be honest, I don't really want to know."

As recently as this spring, underwent more than 20 hours of surgeries because of the bullet lodged in his abdomen and spent more than two months in a hospital.

At 53, he has learned to walk again and is fighting to return to full duty. "I'm not going to let those guys retire me," said of his attackers.

Police swarmed Southeast in the hours after the Glock was fired at Gaines and . The friend of the Hayeses sped in the Altima back to the Prince George's hangout with Romeo Hayes, and, according to court documents, told Ronald Hayes, "I think your brother just killed someone."

Romeo Hayes demanded the car keys, telling his brother he wanted to buy gasoline to "blow the car up" and took off, the files show.

Police in Prince George's County quickly spotted the Altima with its badly damaged passenger side and chased it into the District, where D.C. officers joined a high-speed pursuit covering four miles until Romeo Hayes then jumped out in Northeast. He ran through back yards of the Deanwood neighborhood, breaking a wooden picket fence as he dodged officers and the spotlight of a hovering police helicopter.

Finally hemmed in a warren of fences and buildings, he sat on the porch of an elderly woman's home, where police nabbed him.

Romeo Hayes told police he'd just left a club in downtown and had done nothing wrong.

He was arrested and charged with two counts of assault with intent to kill.

The Glock 17 wasn't on him.

- - -

Rebecca Tomlinson and Michael Brittin came together on a case for the first time in the aftermath of the Glock 17 shootings.

An agent for a decade with the Bureau of Alcohol, Tobacco, Firearms and Explosives, Tomlinson often teams with D.C. police and prosecutors in gun trafficking investigations.

Brittin has spent more than three decades prosecuting major crimes for the U.S. Attorney's Office for D.C.

On the day the two officers were attacked, Brittin, a meticulous senior prosecutor, took over the investigations. Romeo Hayes was in custody in the District and the friend who had driven the Altima was quickly arrested. Tucked into the friend's waistband was a Ruger P345 pistol, one of the guns purchased in the summer buying spree in Virginia.

The friend told D.C. investigators about another gun - a Glock 17 - that he had pulled from a hiding spot in a flower pot and taken to an underground gun trader in the District called "Poppa."

The friend, who was never named in open court because of concerns for his safety, said he had told Poppa "the gun was dirty" and Poppa assured him "he could switch it out for him."

The capture of the Ruger also caught the attention of ATF when it flashed up on a report highlighting quick turnaround times between a gun's legal sale and its seizure during a criminal investigation.

"You have a lot of people sharing and stashing illegal guns" within crews, and in neighborhoods beset by crime "you know you can pick up one if you need it," Tomlinson said.

She and her colleagues set to work tracking the sale of the Ruger. Using the serial number, ATF traced it to a sporting goods store in Ashland, Virginia, court records show, and to the Ruger's buyer of record, Jamal Baker.

Virginia state police databases and records from firearms dealers served up more details: Baker had bought a dozen guns in his own name during an August buying binge.

"We quickly realized this was a huge problem," Tomlinson said.

Surveillance footage from some of the Virginia gun buys showed Baker was not alone during the purchases. But when ATF investigators went to Baker, he would not name his partner.

Brittin, meanwhile, wanted the Glock. Interviews and crime scene analysis had confirmed that 9mm casings at the birthday party and the attacks on the officers had all come from a Glock 17.

When Brittin learned of Poppa, he got a search warrant and investigators scrambled. But the search at Poppa's place came up empty.

Brittin painstakingly scoured internal daily police reports, looking for firearms recovered from crime scenes.

As Brittin struggled to find the Glock, Tomlinson asked federal prosecutors for help identifying Baker's gun-buying partner. The request led her, in December 2014, to Brittin.

He arranged for her to interview Romeo Hayes' friend and driver.

He told Tomlinson that he'd bought the Ruger and the Glock from the man in the surveillance video, Baker's partner. The friend said the man was a rapper named "Stunna," pulling up his music videos on an iPhone.

But who was "Stunna" really?

Law enforcement teams stopped at music recording studios and a concert and got nothing on Stunna before a social media posting exposed him as Lawrence Monte Morgan, investigators said.

He was soon arrested. Investigators didn't turn up the Glock.

Tomlinson had privately assumed the Glock had been made to disappear as part of the cleanup in the days after the shootings but had asked to be alerted if any gun Baker had purchased surfaced at a crime scene.

And she waited.

Brittin continued plowing through internal police reports.

From Tomlinson, he had learned the Glock's serial number: CME244.

And he waited.

They got their hit in the early days of 2015.

The Glock had been tossed under a car after a police chase by a man whose relatives lived in Poppa's housing complex.

The serial number had been obliterated in three places, but ATF still could make out all but the second character. It looked like an H, but maybe it was an M. The visible characters appeared to match Virginia sales records.

With help from the manufacturer, official ATF confirmation came on Jan. 26, 2015 - nearly six months after the Glock first went out on the streets.

Tomlinson and Brittin finally had their gun.

- - -

With the Glock 17 in hand, prosecutors were able to go to court with the weapon used to fire on law enforcement.

The initial buyer, Baker, pleaded guilty to lying on the federal firearms forms.

Morgan, who sold the guns, pleaded guilty to aiding and abetting the making of a false statement in the purchase of a firearm.

Each was sentenced in 2015 to more than a year in prison. They and their attorneys did not respond to interview requests for this story.

The Hayes brothers' friend pleaded guilty to a long list of crimes that included possessing the unregistered Ruger and Glock and his role as the driver on the night of the police shootings.

In February 2016, Ronald Hayes was sentenced to 16 months in prison for being an accessory after the fact for his role in the gun case and the officer shootings.

The shooter, Romeo Hayes, pleaded guilty to eight felonies, including assault with intent to kill and assault with a dangerous weapon for the attack on Gaines.He got 10 years in prison.

At his sentencing hearing in March 2016, Romeo Hayes told the judge he did not remember what happened the night the officers were fired on because he was so high on drugs.

"I do want to apologize to the victims, and I do want to take full responsibility for it," he said.

Gaines, who is still on the force, was at the sentencing hearing, but a prosecutor spoke on her behalf. The shooting was terrifying for the officer and her husband - who also is a police officer - and remained "frightening and difficult" to comprehend, the prosecutor said.

When it was 's turn, he rose with his wife and mother watching.

"Anybody could have been at that light that night," said in court. But if not for his training and instinct to go after Romeo Hayes, there would have been a different outcome.

"If I had stayed the hunted and not become the hunter, I would not be here, your honor." If had been a civilian and not a cop, the detective told the judge, "Mr. Hayes would have got out of that car and finished me."

- - -

Of the 12 guns Baker and Morgan bought in August 2014, six are still on the loose.

The Glock 17 came to rest in a vault in D.C.'s forensics lab in Southwest, waiting to be incinerated with other weapons in now-closed cases.