Zetro is most well known for his time in Exodus, for whom he sang between 1986 and 1993 after being brought in to replace Paul Baloff. Before singing for Exodus, he was the lead singer for the band Legacy (which became Testament after his departure), recording one demo. At the time of his departure of Legacy, he introduced Chuck Billy to Legacy members and joined Exodus. Exodus was disbanded shortly after the release of Force Of Habit. He later rejoined the reformed Exodus from 2001 2004. He later departured from them in late 2004. Tempo of the Damned, again replacing Baloff (but this time under more tragic circumstances), but abruptly quit during the South American tour. He recently hosted the Thrash Against Cancer benefit in 2005 at The Pound in San Francisco, and appeared onstage with Testament at a gig in Concord, California.

His voice is reminiscent of AC/DC's former vocalist Bon Scott, and can be heard on the AC/DC covers that Exodus recorded during the 80's, "Overdose" and "Dirty Deeds Done Dirt Cheap".

In 2006 he and Chuck Billy formed Dublin Death Patrol, an American thrash metal band.