CHICAGO (CBS) —  A lawyer for the estate of Jemel Roberson, a security guard who was shot and killed by a Midlothian police officer over the weekend said a civil rights lawsuit is coming after criminal proceedings take place.

Lee Merritt, who represents Roberson’s child Tristan, the child’s mother and his unborn child said the family is grieving and they want transparency from the authorities in Midlothian.

“That means the prosecution needs to interact with the family and provide regular updates as to the status of their investigation and moving forward with prosecution,” Merritt said.

He said the name of the officer, which has not been publicly released, should be revealed. Merritt said he will be filing a civil rights lawsuit after the criminal proceedings of the case.

Police said a gunman had entered Manny’s Blue Room Lounge in Robbins early Sunday morning, and shot multiple people inside the bar. When officers arrived at the scene, Roberson was holding down a suspect on the ground outside the bar.

“A Midlothian police officer encountered a subject in plain black clothing with no markings readily identifying him as a Security Guard, armed with a gun in the west parking lot,” state police said late Tuesday.

The Illinois State Police account of the shooting early Sunday also contradicts witnesses who said Roberson was wearing a shirt and hat that clearly identified him as security, stating the young man was wearing all black clothing without any markings.

RELATED: State Police Account Contradicts Witnesses In Fatal Police Shooting In Robbins