This image taken from RCMP surveillance video shows Const. Desmond Sandboe on top of Andrew Clyburn at the Lac La Biche, Alta., detachment on Sept. 13, 2009. (RCMP)An Alberta RCMP officer who pleaded guilty to assaulting a prisoner should spend time behind bars, an Edmonton courtroom was told Thursday.

Const. Desmond Sandboe admitted in November to beating Andrew Clyburn, 33, at the RCMP detachment in Lac La Biche on Sept. 13, 2009.

Crown prosecutor Jason Neustaeter told the judge at Sandboe's sentencing hearing that the nine-year RCMP veteran should serve a sentence of six to nine months in jail for the attack.

Sandboe's lawyer Rod Gregory asked for a conditional discharge, arguing his client was overworked and suffering the effects of post-traumatic stress disorder at the time.

Sandboe was among the officers who responded to the slayings of four RCMP officers in Mayerthorpe in March 2005.

"It does not excuse what happened but it certainly explains to a large degree why," Gregory said.

Sandboe expressed remorse and apologized to Clyburn, who was sitting behind him in the courtroom.

The judge will announce a decision on Feb. 7.

According to a victim impact statement read by Neustaeter, Clyburn suffers from memory loss and breathing problems.

Clyburn told CBC News the attack started after he corrected Sandboe when he mispronounced his name.

Video of the attack shows Clyburn slumping to the ground and shielding his head from Sandboe's blows during the 40-second assault.

Sandboe is currently suspended without pay by the RCMP. He is now the subject of an internal RCMP investigation which will resume once the criminal proceedings are complete.