Matthew Leon Mullin III, 65, retired FBI agent

Matthew Leon Mullin III, 65, of Wyncote, a retired FBI agent, died of a heart attack Friday at home.

Mr. Mullin joined the FBI's Philadelphia office in 1976 and was assigned to assist in the investigation of state Sen. Henry "Buddy" Cianfrani. Cianfrani, who chaired the state Senate Appropriations Committee, eventually served 27 months in federal prison after pleading guilty to charges of bribery, racketeering, mail fraud and obstruction of justice.

Mr. Mullin was involved in several other high-profile cases during his 23 years in the Philadelphia office, including the investigation of the 1979 murders of Upper Merion High School teacher Susan Reinert and her two children. Reinert's body was found in the trunk of her car. Her children's bodies were never found. Upper Merion Principal Jay C. Smith was convicted of the three murders and was sentenced to death. His conviction was later overturned.

In 1986 Mr. Mullin assisted in the apprehension of Ramona Joan Thompson of Maryland, who kidnapped a day-old infant, Phillip Worthington, from a Bucks County Hospital and tried to swindle $70,000 from her former boyfriend in exchange for visitation rights after she told him the baby was his.

Mr. Mullin had been a special agent in Atlanta and in New York City before coming to Philadelphia. "There was never a day when he didn't want to go to work," his wife, Margaret Lang Mullin, said. He was a people person, and could just as easily talk to a prisoner behind bars as he could to a fellow law-enforcement officer, she said.

After retiring in 1999, Mr. Mullin was a licensed private detective and then was eastern regional manager for Integrated Biometric Technology, a fingerprinting services company. For the last two years he was a part-time customer service representative for the Blue Bell company QuigMeds. He had time to play golf twice a week, his wife said, and shot 88 two weeks ago, a personal best. He and his wife enjoyed travel and visited Italy, London, and Paris and had recently taken a Rhine cruise. He loved horse racing, his wife said, and had planned to host a Kentucky Derby party on Saturday.

Mr. Mullin grew up in Monmouth County, N.J., where his father managed a horse farm, and his uncle was a steward at Monmouth Race Track. Mr. Mullin worked at the track summers while earning a bachelor's degree from La Salle University. He then served on active duty with the Army Reserve in Fort Bragg, N.C., before joining the FBI in 1970.

He was past president and current secretary-treasurer of the Wyncote Civic Association.

In addition to his wife of 39 years, Mr. Mullin is survived by daughters Mora and Kathleen; son Matthew P.; and a sister.

Friends may call from 6 to 9 p.m. today at St. Luke the Evangelist Church, Easton Road and Fairhill Avenue, Glenside. A Funeral Mass will be said at the church at 11 a.m. tomorrow.

Memorial donations may be made to Melmark Home, 2600 Wayland Rd., Berwyn, Pa., 19312.