Two families whose loved ones were murdered in 2005 have filed a lawsuit against Mercy Fitzgerald Hospital and two psychiatrists, charging gross negligence in the release of a mental patient accused of the slayings.

The families of Douglas Sofield, 42, and of Thomas Rafferty, 67, and his wife, Rita, 55, knifed to death on July 23, 2005, at their Drexel Hill homes, have filed suit in Delaware County Common Pleas Court.

The lawsuit claims that the Darby hospital and doctors were grossly negligent for failing to involuntarily commit Michael Rafferty, the son of Thomas and Rita.

Rafferty, then 29, had been arrested on July 4, after threatening neighbors with a knife, and was taken to Mercy Fitzgerald Hospital's mental-health-crisis center, according to Roy DeCaro, one of the lawyers representing the families.

The lawsuit claims that Rafferty's arrest and pyschiatric history, which included previous trips to Mercy, should have led to his being committed.

One doctor wrote after the evaluation that Rafferty "poses an ongoing risk of danger to himself and others."

However, Rafferty was sent back into police custody, and was released on $500 bail two weeks later, according to the lawsuit.

A statement from Mercy Health System, the hospital's parent company, expressed sympathy for the slayings but said that state law prohibited it from commenting on the lawsuit.

The psychiatrists named in the suit, Lee D. Silverman and Ulhas V. Mayekar, did not return a message from the Daily News left at their office.

Michael Rafferty killed himself in prison on Aug. 18, 2005, while being held for the slayings. He suffered fatal head and neck injuries after hurling himself into a door, officials said. *