Lawyers for accused cinema shooter James Holmes have filed a request to change their client's plea to not guilty by reason of insanity following last summer's (12) Colorado movie theatre massacre.

The suspect stands accused of opening fire just before a midnight screening of The Dark Knight Rises in an Aurora theatre last July (12), killing 12 filmgoers and leaving 58 others wounded.

Holmes was charged with a total of 166 crimes, including 24 counts of first-degree murder and 116 counts of attempted murder, and, during his March (13) arraignment, Judge William Sylvester entered a standard not guilty plea on Holmes' behalf after he failed to respond to the allegations before his court-appointed deadline.

The 25 year old's legal team offered a guilty plea deal to prosecutors in return for a life imprisonment verdict, but the authorities turned it down as they plan to pursue the death sentence.

On Monday (13May13), Holmes' attorney Daniel King asked new judge Carlos A. Samour to accept a plea of not guilty by reason of insanity, according to the Associated Press.

A decision will be made by 31 May (13).