The Crown is seeking a six to nine-month sentence for a nine-year member of the RCMP who pleaded guilty to the assault of a prisoner in his care.

The charge stems from an incident caught on cell block video in which Const. Desmond Sandboe is shown assaulting the prisoner at the Lac La Biche RCMP detachment on Sept. 13, 2009.

The surveillance video, which has no audio, shows two RCMP officers just starting their shift, and leading the prisoner down the hall. The 33-year-old prisoner, who had been unruly and injured in a bar fight hours earlier, believed he was supposed to be released from custody.

The video shows Sandboe lunging at 33-year-old Andrew Clyburn and appears to smash his head into the wall twice. The prisoner is then sent to the ground with the constable swinging his hand towards the man's head.

During this time, two other men can be seen standing behind the constable and the prisoner watching the assault.

After 40 seconds, the prisoner is led back to his cell.

The incident was reported to the RCMP Detachment Commander who then referred it to the Alberta Serious Incidence Response Team (ASIRT), a police body that investigates incidents or complaints of serious injury or death that may have resulted from the actions of a police officer.

The lawyer representing Sandboe, Rod Gregory, said his client's actions were "not a premeditated occurrence and the court ought to take that into consideration."

The defence said his client believed he saw threat cues from victim.

"He perceived the complainant made a quick move toward him. But Gregory said his client did "overreact."

"It may well be that video shows he mis-perceived the threat cue."

Gregory said the constable has accepted full responsibility for his actions. It is claimed the constable suffers from acute stress disorder from responding to the fatal shootings of the four officers in Mayerthorpe in 2005.

His lawyer went on to tell the court that according to a doctor's report, Sandboe has made "significant process."

The defence has asked for a conditional discharge saying if properly composed, "could send a very strong message to other peace officers."

But the Crown said a discharge is not appropriate in this case.

"It was a sustained beating over the course of 40 seconds," said Crown prosecutor Jason Neustaeter.

The Crown has also asked for the judge to consider a possible weapons prohibition for the constable.

The constable was originally charged with assault causing bodily harm but because his victim was already wounded, the Crown was unable to prove what injuries Sandboe might have inflicted.

Sandboe read three type-written pages to the court and repeatedly apologized to his victim, saying he no longer speaks to his own parents out of shame and has been distanced from his RCMP family as well.

The constable has been suspended without pay.

He will be sentenced on Feb. 7th.

With files from David Ewasuk