Zakk Wylde Restrains Obsessed Fan

Zakk was in court Friday in L.A. -- where he testified his 20-year-old neighbor John Radich knocked on his door one day, shirtless, wanting to talk.

Zakk says he sent the guy home -- but the next morning, he noticed Radich had left behind a "sacrifice" containing several bizarre objects, including a guitar covered in Sharpie marker and a boxcutter.