An American psychologist who once worked on the O.J. Simpson case was slated to take the stand on Tuesday but his expertise is being challenged by the defence.

Forensic Psychologist Dr. Kris Mohandie is an expert on assessing and managing violent behaviours and was set to be the final witness for the prosecution.

Dustin Paxton is on trial for the assault and confinement of his roommate and former co worker who cannot be named.

The victim finished testifying last week and he told the court about the extent of his injuries alleged caused by Paxton.

The victim said that he remembers waking up in a Regina hospital, but nothing about how he got there.

The court spent a good part of Tuesday morning determining if Mohandie's testimony was relevant to the case.

Mohandie was expected to counter the defence's claim that Paxton's alleged victim could have simply left at any time.

The defence is challenging the Dr's expertise and the trial has been halted until the judge makes a decision on Mohandie's testimony.