“I am who I am,” he told her. “So please, tell me whether or not you want me to keep talking, because it’s not very pretty.”

Mr. Dexheimer grew up in Chatham, N.J., the oldest of three children born to Eileen Dexheimer, a preschool teacher, and Craig Dexheimer, a longtime director at Lazard Asset Management in New York.

An excellent high school student who aspired to be an architect, he fell in with the wrong crowd, he told Ms. Hancock. He proceeded to tell her things that evening “that should have made her run for the hills,” he said, including the fact that he was addicted to OxyContin and other opioids.

“I had never been that honest with anyone,” Mr. Dexheimer said. “But with Alba it was different, we had an immediate connection, I knew she was someone I could trust.”

He said drugs had left him on the streets of his hometown, his whereabouts often unknown, and desperate for money to support a habit that was destroying his life. “I was stealing everything I could and swindling everyone I could,” he said, “including my own family.”

Mr. Dexheimer went to Lehigh University in Bethlehem, Pa., in September 2004, but in his sophomore year, his drinking and drug use escalated and he was dismissed. “I just sat in my dorm room all day, depressed, drinking, getting high and not going to class,” he said. “When they kicked me out, I had a 0.0 grade point average.”