CHICAGO (CBS) — Cook County State’s Attorney Anita Alvarez on Thursday asked the FBI to assist her in investigating a deadly police shooting that killed two people on the West Side.

While the shooting is being investigated by the Independent Police Review Authority (IPRA), Alvarez said that her office has contacted federal agents for assistance in any criminal investigation as well.

“The State’s Attorney’s Office does not control the pace or process of IPRA, but it is absolutely critical in this case, as in all police-involved shootings, for the investigative agency to get it right so that justice can be served,” Alvarez said in a statement. “The State’s Attorney’s Office will review the results of the investigation when they are presented to our office and will determine if any criminal charges are warranted.”

“This is a deeply disturbing incident that demands a very deliberate and meticulous independent investigation. At this stage, the investigation is being conducted by IPRA, but my office has also contacted the FBI to request their involvement as well.”

CBS 2 has learned that the Justice Department was surprised by Alvarez’s statement, learning about it through media reports. In fact, Alvarez appeared to blame the feds for delays in charging Chicago Police Officer Jason Van Dyke in another deadly police involved shooting.

On Dec. 26, police were called to an apartment building on the 4700 block of West Erie at about 4:30 a.m. for a domestic incident.

In a statement, police said that the officers were confronted by a combative subject and the officers fired their weapons, fatally shooting two people. A 19-year-old man, Quintonio LeGrier, and Bettie Jones, a 55-year-old mother of five who lived in the same building, were killed.

LeGrier’s father has filed a wrongful death lawsuit against the city, claiming his son posed no threat to the police officer who shot him.

LeGrier, a sophomore at Northern Illinois University in DeKalb, was “20 or 30 feet” away from the police officer who shot the teen inside a West Garfield Park home, attorney Basileios “Bill” Foutris told the Chicago Sun-Times on Monday.

The lawsuit was filed on behalf of LeGrier’s father, Antonio LeGrier, whose 911 call early Saturday brought police to the home in the 4700 block of West Erie Street.

The unidentified officer who fired the shots currently works in the 11th District and he’s assigned to the midnight shift. The officer is in his 20s and is a former Marine.

He entered the academy in October of 2012 and graduated six months later in March of 2013.

Under CPD policy at the time he would’ve been a probationary police officer for 18-months, so that means at the time of the shooting, he had only been off probationary status and been a full-fledged officer for a little more than a year.