Four men convicted of ordering and carrying out a string of gangland killings in the Netherlands should be jailed for life, the appeal court in Amsterdam was told on Tuesday.

Three of the four – Jesse R, Mohamed ’Moppie R and Siegfried S – were jailed for life at their earlier trial but the fourth, Dino Soerel, was found not guilty because of a lack of evidence.

Two crown witnesses – Peter la Serpe and Fred Ros – face eight and 14 years respectively. A seventh man, Ali A, who was also found not guilty at the earlier trial, was shot dead in Istanbul at the end of 2014.

Evidence

The evidence from the crown witnesses led to the re-arrest of gangland leader Willem Holleeder at the end of 2014 and strengthened the case against Dino Soerel, the Telegraaf said. He is a witness against Soerel in this trial but is also being investigated for his role in a number of other killings.

Four other men face between 11.5 years and three years, three months in jail.

The appeal process was begun in 2013 and has involved 140 days of court hearings so far. The verdicts are expected in spring 2017.

Killings

Five of the killings under investigation took place in 1993. The others include the murders of property magnate Kees Houtman in 2005 and cafe owner Thomas van der Bijl in 2006.

The 11 are also charged with planning other killings, membership of a criminal organisation, money laundering and the illegal possession of weapons.

By the time the original trial actually started in 2009, some 257 witnesses had been heard during the police investigation, 500 telephones were tapped and the paperwork filled 250 files.