which is their debut album?
In Flames
Killswitch Engage
In Flames
what happened to the lead singer of killswitch engage UNANSWERABLE is it an album? No, it  is an American metalcore band.
wiki:19533770
Killswitch Engage [SEP] Early years and debut album (1999–2001)
In 1999, Killswitch Engage recorded a demo containing four tracks, including "Soilborn", the first song written by the band. The demo was first released at the band's first show, opening for melodic death metal act In Flames, in November 1999. They released their self-titled debut album the following year. Although initially the album was not a financial success and did not land on any charts, it attracted the interest of Carl Severson, who worked at Roadrunner Records at the time. Severson handed "Killswitch Engage" to several Roadrunner representatives. Mike Gitter, a talent agent of the company, contacted D'Antonio, attended several of the band's shows, and offered the band a recording contract with Roadrunner.