During 1993, his last year in Ceremonial Oath, he wanted to write music and combine melodies inspired by Iron Maiden, with the brutality of death metal; something which Jesper stated he had never heard any band do. Now free to control a band, he formed his first one, In Flames, which was considered a side project. The first demo he made with the band was shipped off to the owner of Wrong Again Records, who liked it so much that the owner spoke to the members of In Flames and with the pressure of being signed, the band lied stating they had 13 songs done; intrigued, the band got the deal over the phone. He started in the band as the drummer but switched to guitar by the next year.
