PORTLAND — A second defendant in the Krista Dittmeyer murder case is pleading guilty.

Trevor Ferguson, 24, is scheduled to appear in Carroll County Superior Court in Ossipee, N.H. tomorrow morning, according to the New Hampshire Attorney General’s Office.

Neither the prosecutor nor the defense attorney could immediately be reached for comment.

Ferguson, of Tamworth, N.H., was arrested for conspiracy to commit robbery after the body of Dittmeyer, a 20-year-old mother from Portland, was retrieved from a snowmaking pond at Cranmore Mountain Resort in Conway on April 27, 2011. Authorities said she was the victim of a scheme to rob her of drugs and money.

Dittmeyer’s disappearance prompted an intensive search. Her 14-month-old daughter was found unharmed in Dittmeyer’s car, which was running with its blinkers on and doors open in the parking lot of a nearby recreation center.

Anthony Papile, 29, of Ossipee, N.H., pleaded guilty to second-degree murder in the case last month. He was sentenced to 50 years to life in prison.

Michael Petelis, 29, was arrested for conspiracy to commit robbery.

Authorities have said that Petelis arranged for Dittmeyer to come to his apartment before Papile hit her with a club. The two men bound her with duct tape and put her in the trunk of her car and Papile drove to the ski area and put her into the pond, according to authorities.

Ferguson provided the other two men with a ride back to Ossipee, where they divided money and drugs they got from Dittmeyer, according to court documents. Ferguson got $20 in gas money, according to the documents.