An unidentified man turned in the $850,000 instrument to police, saying he had found it in an alley while walking his dog.
According to Deutsch, the violin, built in 1742 by Sanctus Seraphin of Venice, was stolen from the front seat of her car while she shopped on April 20.
"Just that it's over is so amazingly good," Deutsch said. "I'm at peace. I've been waiting my whole life to get an instrument of this quality, and for it to be gone like this, I didn't think I'd ever get this one back."
The violin had been loaned to Deutsch by collector Peter Mandell. It was insured, but the insurance did not cover theft from an automobile.
The man who turned in the violin will receive a $10,000 reward offered by Deutsch's parents once his version of events is confirmed. "At this point he's just a good Samaritan until we find otherwise," said Detective Don Hrycyk.