A federal lawsuit was filed Monday in the shooting death of a bar security guard by a south suburban police officer over the weekend.

Jemel Roberson, 26, was shot to death by a Midlothian police officer early Sunday outside of Manny’s Blue Room Lounge at 2911 S. Claire Blvd. in Robbins, according to the Cook County sheriff’s office.

Roberson’s mother filed the lawsuit in U.S. District Court on Monday, alleging excessive force by the unnamed Midlothian police officer, who was called to the scene to support Robbins police.

“The shooting death of the Decedent, Jemel Roberson, was unprovoked,” the suit states. “The shooting death of the Decedent, Jemel Roberson, was unjustified. The shooting death of the Decedent, Jemel Roberson, was excessive and unreasonable.”

Many of the details of the shooting were not released as of Monday, but authorities previously said that four people were shot inside the bar after an argument. All four suffered non-life threatening injuries, though it was still unclear who fired the shots that wounded them.

As police were responding to the bar, Roberson was able to catch “one of the perpetrators,” the lawsuit states. Roberson was armed at the time and had a valid Firearm Owners ID card, police said.

Once police arrived, a Midlothian police officer shot and killed Roberson, authorities said.

Sophia Ansari, a spokeswoman for the Cook County sheriff’s office, had previously said that the officer fatally shot Roberson inside the bar. The lawsuit, however, says the shooting occurred outside.

The Cook County medical examiner’s office concluded that Roberson died of multiple gunshot wounds and his death was ruled a homicide.

At least one of the wounded was considered to be a shooter during the initial incident, Ansari said. That person was in custody, but the sheriff’s office was not sure if there was an additional shooter in the incident.

The bar shooting was being investigated by the Cook County sheriff’s office. The shooting involving the Midlothian officer was being handled by Illinois State Police.

Citing the ongoing investigation into the shooting, Nick Valadez, an attorney for Midlothian, said he could not comment on the lawsuit but said in an email: “The Village of Midlothian and its Police Department would like to express their heartfelt condolences to the family of Jemel Roberson.”

Roberson’s mother could not be reached Monday.

Though he worked in the south suburbs, Roberson lived in the Homan Square neighborhood on the West Side.

His landlord, who asked to not be named, remembered him as a thoughtful and caring man. A musician at several churches, Roberson could often be heard practicing playing the organ.

“He was really a very good person — a good, responsible young man,” the landlord said. “When my ex-husband was in the hospital, he called every day just to see how he was doing. And we’re talking about a tenant as opposed to a relative.”

Roberson attended Lane Tech College Prep High School on the North Side, where he had been a member of the basketball team.

Lane Tech tweeted Monday: “We pass along our deepest condolences to the friends and family of Jemel. Jemel had a big smile and a bigger heart. You will be missed.”