After playing pool and drinking at a bar on a Sunday night in February, off-duty Chicago police Sgt. John R. Schuler and his girlfriend headed back to his house on the Northwest Side.

They kept drinking there and argued — about what, the girlfriend later said she couldn’t remember, probably “something very stupid.”

Then, according to police reports, Schuler placed his service weapon — a 9mm Smith & Wesson semi-automatic handgun — on the living-room coffee table in front of her. He called her a “crazy bitch,” she later told investigators and, as he walked to the kitchen, told her: “You should go use that one on yourself.”

The girlfriend, 49, picked up the gun — later telling a detective she thought the safety was on. She stuck it under her chin. And she fired. The bullet splattered pieces of her jaw, tongue, teeth and cheek across the room. She crumpled to the floor but survived and, three months later, is still recovering.

Placed on desk duty after the shooting, Schuler, 49, continues to collect his $111,000-a-year salary while the city of Chicago’s Civilian Office of Police Accountability investigates him for failing to keep his weapon secured, among other things.

The veteran cop already had faced 55 formal complaints about his conduct since he joined the Chicago Police Department in 1991 — over incidents including two DUIs and allegations of abusive behavior toward women, records show.

In one instance while off-duty, court records show, he was accused of throwing a full bottle of beer at a bartender in 2012, striking her in the face, when she refused to keep serving him because he was “severely intoxicated” and acting in an “abusive and combatant manner” to another patron at Tommy’s on Higgins, a Northwest Side bar that’s popular with cops.

The bartender sued City Hall, settling the civil case for $75,000.

Shortly after the incident, Schuler was promoted to sergeant. No disciplinary action was taken against him.

In another instance, while on a downstate hunting trip in November 2008, records show Schuler was driving a Jeep and failed to navigate a bend in the road — he said he swerved to avoid a raccoon. His vehicle flipped and landed about 10 feet from a house. Schuler was taken to a hospital to be checked out. His passenger, another Chicago cop, declined medical attention.

After refusing to take a blood or breath test, Schuler was arrested by an Illinois state trooper for driving under the influence, and his driver’s license was suspended. It was his second off-duty DUI since becoming a cop, records show. The police department suspended him for five days — the same punishment he got for the other DUI, in 1998.

Though departmental rules say Chicago cops can’t be intoxicated even while off-duty and even if they aren’t driving, a Sun-Times investigation last year found that officers usually face little punishment over alcohol- and drug-related incidents. That finding was based on an examination of nearly 400 officers — including Schuler — investigated by the department between 1997 and 2014 over alcohol or drug use. The Sun-Times reported that:

• 198 officers were given suspensions ranging from one day to an indefinite period.

• About 20 percent of those cases were over incidents while the officers were working.

• 33 of the cops resigned. Another 18 were fired or otherwise forced out.

• 101 cases were closed without any disciplinary action, with a finding the allegations were false or hadn’t been proven.

Schuler — who along with his three siblings followed in the footsteps of their father, a retired high-ranking cop, to join the Chicago Police Department — won’t comment. One sibling — older brother Nicholas Schuler Jr. — left the police department and is now the inspector general for the Chicago Public Schools.

According to police reports, John Schuler told officers investigating the shooting that his girlfriend of two and a half years had gotten “really snotty” with him, that he told her, “I’m not dealing with this, I’m going to bed,” and that he placed his gun on the coffee table, where he usually left it. He told them she shouted his name, and he turned and saw her shoot herself.

The sergeant had been drinking, records show, though they don’t say whether he was tested to see whether he was intoxicated.

His girlfriend was. Her blood-alcohol level was .245 percent — more than triple the .08 percent legal threshold at which a driver is presumed drunk under state law.

Responding officers kept Schuler from washing his hands for a couple of hours until they tested him for gunshot residue to see whether he fired the weapon or was nearby when it was fired. The police didn’t release those test results.

That he was tested differs from the way the police handled another shooting on the Northwest Side involving a cop — the off-duty death in 2015 of Sgt. Donald Markham, who was found dead in his bedroom from a head wound. Markham had been arguing with his police officer-wife Dina Markham, but she wasn’t tested for gunshot residue, and the investigation into his death, which was ruled a suicide, was marked by other irregularities, the Sun-Times has reported. The FBI got involved after getting a tip, brought in a forensic pathologist to review the case and told the police and Cook County medical examiner’s office they should reopen their investigation of Markham’s death as a possible murder — a finding the police and medical examiner rejected.

In another case bearing similarities to the shooting at Schuler’s house, the police found that a woman named Catherine Weiland shot herself in February 2009 with Sgt. Steven Lesner’s gun after Lesner came to her apartment hours after responding to her call to police for assistance at a bar. Lesner told investigators he left his gun out when he went to the bathroom in her apartment. Following Sun-Times reports raising questions about Weiland’s death, the Chicago Police Board fired Lesner in 2014 — five years after the shooting — for failing to secure his weapon.

Neither the woman who shot herself with Schuler’s gun nor her lawyer would speak with the Sun-Times.

Fifteen months before the shooting, she and Schuler — a twice-divorced father of two — were involved in another incident that brought out the police. Schuler had been drinking at a bar on the Northwest Side where his girlfriend — a mother of four who is in the middle of a divorce — worked.

Her husband came in and punched Schuler in the mouth, according to police reports. The woman told officers her husband had punched her boyfriend. The husband was arrested for battery. The charge was dismissed when Schuler failed to show up in court.

Detectives investigating the shooting at Schuler’s house interviewed the woman in her hospital room eight days after the shooting. She was still unable to speak, so the detectives conducted the interview in writing. Here’s a portion of their exchange, according to a verbatim transcript the police released in response to a public records request:

Question: What happened?

Answer: John and I got into an argument and he as always was very harsh with his words. John set the gun down in front of me told me to go use it. I thought there was a safety on his gun but guess not that why I’m here.

Q: Did argument start at [redacted]? Did something happen at [redacted]?

A: John plays pool 4 days of week. Drinks every night looses his cool, temper with anyone or thing in his way. To be honest I don’t know what started our argument and Im sure it was over something very stupid.

Q: Did you shoot yourself or did someone physically make you do it?

A: I shot myself but he put the gun on the table in front of me saying you should go use that one on yourself.

Q: Has he done that before?

A: No. John has physically beat me up to the point where he’s pissed of at his brother [redacted] because he had to write up an [Internal Affairs] report on him. I have pictures, text messages, phone calls to a good friend of mine to prove these allegations.

Q: Did he always leave a gun out?

A: Yes. Is always on the coffee table or upstairs in the drawer.

Q: Why did you put gun to your face and pull the trigger?

A: He told me to because he said I was a crazy bitch but dear God I didn’t think it would go off.