The man would not leave Jacqueline Torres alone.

He had harassed and stalked her every day for two years. He broke into her apartment and beat her, her lawyer would later tell a judge. Ms. Torres was so frightened that she quit nursing classes and a secretarial job to avoid him. When she told him she was marrying someone else, he threatened to kill her, she said.

That was when Ms. Torres decided to get a gun.

In the spring of 1992, she bought a used handgun for $75. When the man, Peniel Martinez, called her a few months later in July, Ms. Torres invited him to her Manhattan apartment.

She had never shot a gun. She had just three bullets — what came in the pistol.

“I had to stop him,” Ms. Torres, now 60, said at her former defense lawyer’s office in Manhattan, her service dog, Maximus, beside her. “It was his life or mine. I said, ‘Come and get it.’”