According to a spokesperson for the Aachen court where the trial is underway, Boere said he had merely been following orders while working for the German occupiers.
The former Nazi is accused of shooting three Dutch resistance fighters. Prosecutors say that the murders were among 54 perpetrated by the Nazi killing squad Silbertanne, or "Silver Pine," against Dutch civilians thought to be part of the resistance. Among the victims were a bicycle dealer and a pharmacist. Relatives of the victims are attending the trial as joint plaintiffs.
Boere also told the court that his superiors threatened him with violence if he did not maintain absolute secrecy about the murders. His admission came after the defence submitted a new appeal to the court to dismiss the case.
A Dutch court sentenced him to death in absentia for the crimes some 60 years ago, but the ruling was later changed to a lifelong prison sentence. Boere never served the sentence, fleeing to Germany in 1947. Authorities between the Netherlands and Germany have been bickering about his fate ever since.
In April 2008, Boere admitted to German news magazine Focus that he was guilty of the shootings. In a later interview with Der Spiegel he said he had been following orders which he thought to be correct at the time.
The trial, which began on October 28, can only take place for short sessions to accommodate the deteriorating health of the defendant, who lives in an assisted care facility. A doctor must also be present at all times.
On Tuesday, the court planned for the trial to continue for another five days. The verdict was initially expected on December 18, but has been pushed back to February 19.
The case is being closely followed along with that of 89-year-old John Demjanjuk, a Ukrainian-born former guard at the Sobibor death camp in Nazi-occupied Poland. He is currently on trial in Munich for allegedly aiding in the gas chamber deaths of some 27,900 Jews in 1943.