On 3rd of October 2006 Joost was murdered with an axe by Long-Long G., the mentally unstable ex-partner of Joost's adoptive father. After the murder Long-Long G. cut Joost's body in pieces and proceded to cook the lifeless remains in oil. The remains where then thrown away in several garbage containers and ditches across Alphen aan den Rijn, The Netherlands. Long-Long G. was arrested a few days after the murder and confessed to the crime in March 2007. Long-Long G. was eventually deported back to his home country of China. The murderer was an avid follower of the Chinese spiritual practice known as "Falun Gong".
Vastenhouw's murder is considered to be one of the most hideous crimes that ever occured in The Netherlands.
After Joost's death Calslagen decided not to continue activities without him.