A photographer pleaded guilty to third-degree murder and other charges Monday for fatally stabbing a Canadian porn actress in a dispute over money after a photo shoot.

Anthony Frederick (search), 47, of Lower Providence, admitted in Montgomery County Court that he stabbed Natel King (search), who went by the stage name Taylor Sumers, at a studio in the Philadelphia suburb of Conshohocken last February.

Frederick told authorities he killed King, 23, of the Toronto area, in self-defense after she posed in a bondage shoot that they arranged online, prosecutors said.

When he didn't have the money to pay King, she threatened him with a hunting knife that had been part of the shoot, county District Attorney Bruce Castor said. Frederick took it from her and stabbed her, Castor said.

Defense attorney Richard Winters said last week that his client was very remorseful. Winters did not immediately return a telephone message Monday.

Frederick faces 251/2 to 51 years in prison and agreed to testify against his former assistant, Jennifer Mitkus (search).

Mitkus, 30, allegedly helped clean up the murder scene and stabbed the dead woman, Castor said. She is awaiting trial on charges of abuse of a corpse, hindering apprehension and other offenses.

Frederick and Mitkus initially told police investigating King's disappearance that King left the studio Feb. 29, 2004, after being paid $900. But police searched Frederick's studio and found evidence of King's blood there and inside Frederick's sport-utility vehicle.

The body was found almost a month later in a ravine near the Schuylkill River in Whitemarsh.

King died of multiple stab wounds to the chest and neck and also had deep stab wounds on her hands, apparently inflicted when she tried to defend herself.

A sentencing date was not set.