was he also a part of any other band apart from former one?
Yes,  Arma Angelus
Pete Wentz
Arma Angelus
who is lead singer of fall out boy Patrick Stump what is fall out boy? It  is an American rock band. when did this band form? 2001 can you name some members from this band? The band consists of lead vocalist and rhythm guitarist Patrick Stump, bassist Pete Wentz, lead guitarist Joe Trohman, and drummer Andy Hurley. where is the bassist from? Wilmette, Illinois
wiki:12751405
Pete Wentz [SEP] Introduction
Peter Lewis Kingston Wentz III (born June 5, 1979) is an American musician, singer, songwriter, A&R consultant, author, and record executive. He is best known as the bassist and lyricist for the American rock band Fall Out Boy, since 2001. Before Fall Out Boy, Wentz was a fixture of the Chicago hardcore scene and was the lead singer and songwriter for Arma Angelus, a metalcore band. During Fall Out Boy's hiatus from 2009 to 2012, Wentz formed the experimental, electropop and dubstep group Black Cards. He owns a record label, DCD2 Records, which has signed bands including Panic! at the Disco and Gym Class Heroes.