Kindness Lessons Cost Sons Their Lives, Mother Says : New York: One boy was stabbed to death trying to stop a robbery 11 years ago. This month, another one was shot to death, also while trying to stop a robbery.

Christina Vaccarino always taught her children to be kind and to help people in need. They learned the lesson, perhaps too well.

Attempts to help others have cost two of her sons their lives.

Vaccarino buried one son, Edward, 11 years ago after he was knifed to death trying to stop a street robbery. She relived the tragedy this month, when another son, Glenn Iscoe, was shot to death trying to break up a bagel store holdup.

“I blame myself for my son’s death,” Vaccarino said at her home in Queens. “In our family, whether you know a person or not, you help them out when they’re in need. That’s a lesson I’ve taught my children.”

“I know he was listening to my words when he went to help those people,” she said, her voice choked with sorrow. “Maybe he’d be alive today if I hadn’t taught him that.”

Iscoe, 35, was taking a break from driving his livery cab early one morning and stopped for coffee at the bagel shop. As he waited in line, a skinny, nervous man in front of him pulled out a gun and announced a robbery, pointing the gun at the two employees behind the counter, police said.

“Hurry up! Hurry up or somebody’s going to get killed!” the robber shouted as the employees began putting cash in a paper bag.

Videotape from a store surveillance camera, released by police, graphically captured Iscoe lunging at the robber and trying to knock the gun from his hand.

He missed, and when he lunged a second time, the suspect fired once into Iscoe’s left temple. The robber then coolly collected his booty--$178 in cash and Iscoe’s wallet--and left.

“I can’t help but think he’d be alive today if he didn’t try to help,” said John DePalo, manager of the bagel shop. “He made the ultimate sacrifice to save someone.”

The employees were not injured.

Police have long warned citizens about the dangers of trying to stop a crime.

“People get robbed every day,” said Lt. Louis Pagnotta, who is heading the investigation. “Ninety-nine percent of them give it (property) over. Here’s a guy who took it upon himself to try and stop a crime. He tried to do the right thing, but it didn’t turn out right.”

Iscoe’s younger brother also died trying to be a good Samaritan. The off-duty, 23-year-old correction officer interceded in a street robbery outside a Queens movie theater in 1983 and was stabbed to death.

“You have no choice but to keep going,” Vaccarino said of losing two sons so violently. She has two other children, Gary, 32, an attorney from West Palm Beach, Fla., and Kelly, 24, also of Queens.

She tells a story that epitomizes Glenn: He was driving a young woman in his cab to meet her boyfriend at a street corner. Instead of dropping her off in the dark of night, he waited with her. When the boyfriend failed to show up and the girl had nowhere to go, Iscoe brought her to his mother’s home.

The next morning, Vaccarino chided the young woman for coming home with a stranger, saying, “He could have beaten you up or brought you someplace bad.” But the girl told her: “ ‘I could tell from his face and the look in his eyes that he was a wonderful person . . . and I knew everything was going to be OK.’ ”