Mary Nowak, oldest Salem Citizen Police graduate, 99

At age 87, she became the oldest graduate of the Salem Police Department’s Citizen Police Academy, and at 95, she tried out a Jet Ski on Lake Ossipee in New Hampshire.

“She always taught us to keep learning, no matter what,’’ said her son Paul of Topsfield.

Mrs. Nowak, who had 25 great-grandchildren and was affectionately known by family and friends as “Granny,’’ died Monday at the Kaplan House in Danvers following a stroke. She was 99.

Born in Poland, Mrs. Nowak was brought to America as a baby and kept in touch with her roots through the heavily Polish St. John the Baptist Catholic Church in Salem, where she became the oldest active member.

“St. John’s has always been part of my life,’’ Mrs. Nowak told the Globe in 2003, when the parish celebrated its 100th anniversary.

“Coming here always made me appreciate so much more where I came from,’’ she said. “Going to church here, knowing I would be with the Polish people, gave me something to look forward to.’’

Mrs. Nowak was a familiar presence in Salem. She took daily walks down Derby Street and lived most of her life in the three-decker where she and her husband, Anthony, a house painter and electrician, raised their four children. He died of a heart attack in 1961. She never remarried.

Hard work was a hallmark of Mrs. Nowak’s life, and she did not want to stop. She worked for Hygrade Incandescent Lamp Factory, Pequot Mills, and Shetland Industries, all on the North Shore. She was in her 70s and working for Pilgrim House Nursing Home in Peabody when she was forced to retire, her son said.

She kept a close network of friends throughout Salem, elders who looked out for one another as they met for chats at the House of the Seven Gables or at the senior center, her family said. She also enjoyed meeting with seniors from the Peabody Council on Aging.

“She taught us all how to live life to the fullest and to cherish our family and friends,’’ said family friend Bill Millette of Carmel, Calif.

Millette recalled his wedding day when “Aunt Mary’’ pinned $5 on his tuxedo for a dance. “I’m going to get my money’s worth,’’ she told him and requested a polka.

“I don’t think my feet ever left the ground,’’ Millette said.

When Salem police began a Citizen Police Academy, Mrs. Nowak signed up. She listened to frantic 911 calls from a battered woman while learning how police handle domestic violence and rode with officers chasing a shoplifting suspect.

When an officer requested backup, Mrs. Nowak quipped: “What do you need backup for? You’ve got me,’’ she told the Boston Herald in 1997.

Her son, longtime Salem City Councilor George Nowak, was a North Shore police officer for 20 years. He died in 1993 at age 54 after suffering a heart attack while chasing two suspects.

One of Mrs. Nowak’s happiest moments came when she was reunited with her older sister, Anastasia Forys, more than 50 years after they parted as children in Poland.

Their parents, Gregory and Katherine (Sucheska), had been saving money to bring Anastasia to Salem when World War I broke out and Anastasia fled to France.

Mrs. Nowak traveled to Paris to see her. “It was like two teenaged girls getting together,’’ said Paul, her son. Anastasia died at age 92.

In addition to her son, Mrs. Nowak leaves two daughters, Geraldine Cosgrove of Danvers and Kathryn Estomo of Oxnard, Calif.; 12 grandchildren; and 25 great-grandchildren.

A funeral Mass will be said at 10 a.m. today in St. John the Baptist Catholic Church. Burial will be in St. Mary’s Cemetery in Danvers.