SHELTON, Wash. - A British Columbia man accused of slashing his stepdaughter's throat pleaded not guilty in a Washington state courtroom Monday to first-degree murder.

A court-appointed lawyer entered the plea on behalf of Peter Wilson, 29, during a brief arraignment hearing in Mason County Superior Court.

Five-year-old Clare Shelswell was killed in late June while vacationing with her family in Hoodsport, near Seattle.

A prosecutor filed the murder charge on Friday, along with a notice of intent to seek an exceptional sentence, said Ronald Sergi, Wilson's court-appointed lawyer.

Sergi said a straightforward first-degree murder conviction for someone without a criminal history would typically result in a sentence of 20 to 25 years in the state. The notice of intent means a judge could impose an extended sentence of up to life in prison.

"I don't expect the prosecutor to seek a true life sentence," Sergi said in a telephone interview from Shelton, Wash.

He said in filing the notice, the prosecutor is alleging deliberate cruelty and violation of a position of trust. The prosecutor didn't immediately return calls for comment.

Wilson appeared in court Monday in handcuffs and wearing a bullet-proof vest, and said nothing in the courtroom.

"He seems OK, I'm able to talk to him," Sergi replied when asked about the emotional state of his client.

He noted the vest was unusual, but said he wasn't aware of threats against his client and didn't know why he was wearing it.

Police allege the man confessed to the slaying after they responded to a 911 call from the holiday home where they found the girl's body in a pool of blood.

Wilson and his wife have told police he takes medication for bipolar disorder.

Sergi couldn't say whether he would argue his client shouldn't be found guilty for reason of mental illness.

Wilson's next court appearance has been set for Aug. 9.