The job often took him out of state, where he had to confront people who were not happy about being discovered.
It was all about the kids - getting the money they deserved and returning them to their homes. It was the passion that drove Bill McMonagle day and night, and often on the weekends.
"He was a bulldog," said Jerome A. Zaleski, who, as administrative judge of Family Court in the 1980s, worked with Bill. "He was just completely dedicated to his duties."
Another former colleague said: "Bill was like the Northwest Mounted Police and the U.S. Postal Service. He always got his man, regardless of the weather conditions."
William J. McMonagle, a former Marine and devoted family man, died of cardiac arrest April 7. He was 69 and lived in Fairmount.
His wife, the former Cheryl Leibert, accepted the fact that sometimes a night out with her husband was interrupted by a summons to find a lost child or to capture a deadbeat dad.
"It was the way it was," she said. "Always the kids were first. I was proud of him."
Bill worked out of a basement office at Family Court, 11th Street near Chestnut. He was in charge of a group of investigators who were equally devoted to their jobs. Often they could track down the deadbeats and the missing children with computer and phone records, voting lists, car registrations, military records and other tools of modern investigations.
But many times it was a matter of going into people's homes, taprooms or offices and confronting the malefactors face-to-face.
"He had a remarkable record of collecting money," Zaleski said. "He raised an immense amount of money that went to mothers who desperately needed the support.
"Sometimes he worked with the police, but often he did it alone. He was fearless."
Holidays meant nothing to Bill. He spent one New Year's Eve in a nightclub waiting for a singer who owed several thousand dollars in child support. The man hid in the basement, but emerged when Bill threatened to shut down the show.
Bill would get leads from newspaper stories, like the deadbeat minister who got a headline for barring AIDS patients from his church. Bill looked into the files and found that the preacher owed child support.
To bolster his staff, Bill often used bounty hunters, whom he called "private contractors," usually former law-enforcement officers who were paid a fee for each arrest.
In a Daily News story in 1995, reporter Ron Avery wrote that Bill "once collared the winner of a $3 million state lottery. He has arrested a guy trying out for the Eagles, a boxer who had just fought a title bout at Convention Hall, and three professional basketball players."
If they owed money for child support, nobody was safe from Bill McMonagle's persistent and patient dedication.
Bill was born in Philadelphia to Michael and Sarah McMonagle. He graduated from Cardinal Dougherty High School and entered the Marine Corps. He served stateside.
"He was proud of having been a Marine," his wife said. "We have a Marine flag outside the house."
Bill was also proud of his Irish heritage and named his bulldog Guinness. He retired in November 2009.
"He loved Philadelphia," Cheryl said. When Bill could find the leisure, he liked nothing better than walking with Guinness along Kelly Drive, taking in the quiet ambience of the Schuylkill river valley, far away from angry deadbeats and lost children.
Besides his wife, he is survived by a son, Damien DiPentino; a daughter, Jennifer Leibert; two sisters, Sarah Hasson and Mary Nowak; and one grandchild.
Services: Were April 12. Burial was at Holy Sepulchre Cemetery, Cheltenham.