After serving a few years he was released, and was involved in a money laundering scheme. His offending escalated until he was participating in armed robberies of security vans that occurred so  frequently that they led to greatly increased security. He left the country for a time, but on  14 January 1989 he was one of those who kidnapped former Belgian prime minister Paul Vanden Boeynants, releasing Vanden Boeynants on  13 February 1989 for a reportedly huge ransom.
Suffering severe withdrawal symptoms in prison, and after a transfer prevented him joining  an escape with his accomplices, the by then 40-year-old was apparently unable to cope with the prospect of serving a long sentence. He hanged himself from a 130-centimetre (4'3")-high radiator in a Belgian jail cell in 1993. He was at one time considered a likely suspect as the so-called 'giant' of the Brabant killers, but unlike the relatively small-time robberies of the Brabant gang, Haemers's crimes were always aimed at high-value rewards.