In late 1960, Dion decided to leave the group (the decision partly due to a heroin abuse problem), but the Belmonts carried on with Mastrangelo singing the lead vocal parts.
Dion decided to leave the group (the decision partly due to a heroin abuse problem). This was in late 1960. The Belmonts carried on with Mastrangelo. The Belmonts were singing the lead vocal parts.