Michael Peter Nadolnick, a convicted sex offender, admitted to escaping from custody last year and trying to carjack a Calgary woman. (Karen Wade/CBC)

A convicted sex offender has pleaded guilty to three charges after he violently tried to escape custody in November.

While being escorted to a medical appointment, Michael Nadolnick, 45, struck a corrections officer and ran towards a pick-up truck as it pulled out of a city parking lot.

Nadolnick shoved the female driver out of the vehicle and was about to drive off when more corrections officers arrived and recaptured him.

He pleaded guilty on Monday to assaulting a police officer, robbery and escaping lawful confinement.

Nadolnick has a lengthy criminal record.

He was convicted of eight break-ins in Calgary, Lac La Biche and Prince Albert, Sask., between 1985 and 1996. He served 32 months for a 1998 sexual assault and two months for a 2002 assault on a police officer in North Battleford, Sask.

Nadolnick was sentenced to six years in prison in 2003 for aggravated assault.

He was released from the Bowden Institution in May 2007 to a halfway house, rearrested a month later for failing to return to that halfway house, and released again into the Calgary area in Septmeber 2008.

Nadolnick also faces a dangerous offender hearing for hijacking a man's truck and then kidnapping and sexually assaulting a young woman in 2008.

He would serve an indefinite sentence if he is declared a dangerous offender on Feb. 1.