Days before his death-penalty trial on charges that he murdered his girlfriend's 14-year-old daughter, a Montgomery County man is the focus of a 2006 triple-slaying probe in Philadelphia, court records show.

Montgomery County prosecutors unsealed court documents today that identified Mark Patrick O'Donnell, 48, of Plymouth Township, as a "possible suspect" in the deaths of William Fowler, 53; his wife, Estella, 50; and their son, John, 20, who was quadriplegic.

The Fowlers were fatally shot in their home in the 3200 block of Tulip Street in Port Richmond on May 21, 2006, at 1:04 a.m. Philadelphia police attempted to contact O'Donnell, who worked as a nurse for the family. He ignored a grand-jury subpoena, according to a search-warrant affidavit.

The affidavit says that Philadelphia detectives contacted Montgomery County prosecutors after O'Donnell's arrest in the Dec. 7 rape and strangulation-murder of Ebony Nicole Dorsey, a Wissahickon High honor student. Police said the teen had been baby-sitting O'Donnell's 4-year-old daughter at his home so that he could spend the night smoking crack-cocaine with Dorsey's mother, Danielle Cattie, 34, of Whitpain Township.

Philadelphia investigators wanted Montgomery County officials to execute a search warrant to obtain a DNA sample from O'Donnell, who has been in custody since his arrest in December. Montgomery County First Assistant District Attorney Kevin R. Steele had the record sealed because it makes reference to a secret grand-jury investigation in Philadelphia and because its release could have hampered investigators in both cases, court records said.

Steele, who said he did not know whether O'Donnell's DNA matched evidence in the Fowler case, said today that he had to unseal the documents because O'Donnell's defense attorney, Thomas C. Egan 3d, is entitled to review them before the murder trial, scheduled to begin Tuesday.

Contact staff writer Kathleen Brady Shea at 610-701-7625 or kbrady@phillynews.com.