(CBS) — A police officer’s gun puts a bullet in a friend’s head. The officer claims it was an attempted suicide and that his friend shot himself. The victim’s family says that’s not true.

2 Investigator Dave reports.

Michael LaPorta, called “Mikey” by his family, is a gun-shot victim and needs 24-hour care. He has had nine surgeries and is paralyzed on the right side.

It happened four years ago and his mother remembers the fear from that day.

“I was screaming,” Patricia LaPorta says. “I was devastated.”

Patricia and Mike LaPorta Sr., accuse Chicago Police of failing to fully investigate.

“His life was turned upside,” says Mike LaPorta Sr. “Everybody’s life was turned upside down.”

LaPorta Jr. and his friend Patrick Kelly, a Chicago police officer, were hanging out at some local bars until nearly four in the morning. They ended up at Kelly’s house, where Michael LaPorta Jr. sustained a gunshot wound to the head.

Kelly called 911 and said: “I just had a friend that committed suicide.”

A report says Kelly told police he had his gun secured in his bedroom, but he could not remember where. And Kelly says LaPorta took it and shot himself.

According to a police report, when help arrived Kelly was “highly intoxicated, belligerent and very irate.” The off-duty police officer was arrested for swinging his arms at a female police sergeant.

The LaPortas are suing the Chicago Police Department claiming the agency knew Kelly had a history of excessive force and misconduct complaints — 15 of them — but allowed him to remain on the force.

“There are many red flags here,” says attorney Tony Romanucci, who represents Michael LaPorta.

He says there are serious issues with how the shooting was investigated.

“The lab reports came back and there is no evidence of fingerprints on the gun,” Romanucci says. “Now, somebody held that gun and shot it.”

Romanucci also questions how police reports say Kelly held LaPorta, rendering aid, but photos taken show no blood on Kelly.

The LaPortas do not believe their son shot himself. They believe someone else pulled the trigger, and they are not satisfied with answers they have gotten from the Chicago Police Department.

“After four and half years,” Patricia LaPorta says, “how long does it take?”

Attempts to ask Kelly questions about the shooting were unsuccessful.

Sources say disciplinary action was recommended for Kelly but would not say if it was related to the shooting of LaPorta or his arrest for swinging his arms at a responding officer. The Chicago Police Department says Kelly filed a grievance that has yet to be heard.

In the meantime, he is on full duty, working as an officer.