pics in MAYH reissue

Ok.. so the line-up for MAYH was Mike, Pete, and Lopez. Mendez wasn't on this album. But in the reissue of the album, there's 2 pictures w/ 4 guys. Pretty sure that 4th guy is Mendez. Was he officially in the band but just not on the album or something. Anyone know?
 
mikael played the bass on mayh with a fretless i believe (check the equipment section on opeth.com). anyone know if he has done any other bass tracks for opeth?