The University of Colorado has hired a former US attorney to conduct an independent investigation into how the school handled the man accused of the Aurora massacre, who was a graduate student at the University.

Robert Miller, a formal federal prosecutor of Colorado began the investigation last week, said the University in a written statement.

"The University is doing everything it can to fully cooperate with the criminal investigation. Additionally, we are doing everything we can to understand how the university's systems and processes functioned in this situation. Bob Miller comes to us with a stellar reputation for diligence and integrity. We have given him broad latitude to conduct his review," University of Colorado President Bruce D. Benson said in a statement.

Apparently, the probe was requested by the University of Colorado Denver chancellor Donald Elliman, who earlier said he believed University personnel 'did what they should have done' in dealing with Holmes.

"Our resolve rests with understanding all the facts so we can assist law enforcement and other authorities in ensuring that justice prevails," Elliman said in a statement announcing the review.

Holmes was charged this week with 24 counts of first-degree murder and 116 counts of attempted murder for the shootings at the July 20 midnight showing of 'The Dark Knight Rises' in Aurora, Colorado. The suspect was a doctoral student at the University's Anschutz Medical Campus until June, when he withdrew from the program.

Earlier this week, KMGH-TV, an ABC-affiliated TV station citing anonymous sources reported that the University psychiatrist Dr. Lynn Fenton had tried to discuss Holmes with the school's Behaviour and Threat Assessment team. The University website says the BETA team consists of 'key' staff members from various CU departments who have specific expertise to deal with assessing potential threats on campus.

It's not clear when Miller is expected to complete his review. Nor is it clear how much of his report will be released to the public. The University said it is under a court order that bars it from discussing matters connected to the criminal investigation; it must also follow laws related to the release of some types of information, reports CNN.