Arthur J. Walker, a conspirator in one of the biggest U.S. spy cases since World War II, was a surprisingly trusting soul.

When FBI agents wanted to talk to him in 1985 after arresting his brother John on suspicion of espionage, Walker chatted, over several sessions, for a total of 32 hours, without a lawyer.

After U.S. District Judge J. Calvert Clarke Jr. convicted him of espionage, Walker was given a life term but was eligible for parole. Walker, who made $12,000 for selling classified documents to Soviet agents through his brother, died July 5 in a federal prison in Butner, N.C. He was 79.

John Walker was cast by authorities as the espionage ring’s amoral mastermind, a manipulator who got his son Michael, his older brother Arthur and his best friend Jerry Whitworth to join him.

John is incarcerated in the prison where his brother died.