Mary was so devoted to caring for the incarcerated that for a time she opened her former home in Germantown as a halfway house for freed prisoners trying to return to society.
It wasn't always a pleasant experience. She was ripped off occasionally, once by a former inmate who could not kick a drug habit, and she had to change her locks.
"She put her home where her mouth was," said her sister Catherine, a lawyer in Brooklyn, N.Y. "She was courageous in her friendships, but she was not a pushover. She was very bright and practical."
Among the characteristics that endeared Mary to her family and her many friends, besides her tremendous compassion and love for others, was her sense of humor, which tended to be on the dry side and tinged with sarcasm.
Donna Dunleavy, a high-school classmate and friend for more than 45 years, said Mary "had a silly streak. She could be extremely silly, and she had a great laugh. She would laugh and laugh."
"She had a generous heart," Donna added. "She cared about people."
Mary was born in Philadelphia to the late Francis J. Hanssens and the former Teresa Caroselli. She grew up in Frankford.
She attended the Ancilla Domini Academy in Germantown, operated by the Handmaids of the Sacred Heart of Jesus.
"Some nuns there had an impact on her life," her sister said. "She was always interested in social-justice issues, and she joined the order thinking it would be a good place to do that kind of work."
And it was for a while. She taught and worked with prisoners at Graterford and Holmesburg, but eventually she felt that being in the order was an impediment to her goals. She left after 16 years.
She took undergraduate classes at Villanova University and later got her law degree from Temple University.
She worked for the Pennsylvania Prison Society, where she was director of community services. She joined the Pennsylvania public-defender's office in 1992 and the federal office in the early 2000s.
"She was incredibly hardworking," McHugh said. "She was smart, organized and totally dedicated. She was compassionate and humble and had no ego.
"She had a great sense of humor. She saw humor in things that others might have missed."
Ginger Jenkins, a member of the Sisters of St. Joseph who worked with Mary in prison ministries, said she lived near Holmesburg Prison and got permission from the order to volunteer there.
"That's how I met Mary," she said. "We practically lived in Holmesburg. She had tremendous love for the underdog. And she worked like a dog. She never stopped.
"She was a very holy woman. She was so free and broad in her thinking. There was no other way that she could be."
Mary was an excellent athlete in her youth and played sports in school, including basketball. She excelled at tennis. She was a member of Dragon Boat teams and traveled as far as Australia to participate in races.
"She was a fun-loving sister," said her brother Christopher. "She got my son into surfing. She lived to bring joy into others' lives."
Mary loved Cape May and would spend time walking along the beach, enjoying the ocean, which seemed to revive her. She liked to watch the birds along the seashore.
She was also a serious Phillies fan. She and her mother, who lived nearby, would watch every game on TV.
Mary also loved music. She played the guitar and violin and taught her nephews and nieces to play.
Besides her mother, sister and brother, she is survived by three other brothers, Francis, Robert and David, and three other sisters, Barbara Reed, Margie McGrath and Teresa Clark.
Services: Memorial service 11 a.m. tomorrow at the Church of St. Luke and the Epiphany, 330 S. 13th St. Friends may call at 10 a.m.