The man was "determined to kill" Reker and stop her from becoming mayor, the prosecution said at the opening of the Düsseldorf trial on Friday.

According to the indictment, the defendant Frank S. approached the politician at a campaign event on October 17, and wounded her using his hunting knife. He proceeded to injure four more bystanders at a market square, but offered no resistance when the police turned up.

Then-candidate Reker managed to survive the attack after being rushed to surgery. She was voted in as the mayor of Cologne on the following day, while she was still in an artificial coma.

Stabbing over policy

Frank S. acted "maliciously" and out of "base motives," prosecutor Lars Otte said on Friday.

The motive for the attack, according to the prosecutors, was Reker's welcoming stance towards refugees and foreigners arriving in Germany. Before running for mayor, Reker was a coordinator in charge of housing refugees in Cologne.

On the other hand, the defendant was known to the authorities for his contacts with right-wing extremists and neo-Nazi groups. The unemployed house painter also spent time in prison between 1997 and 2000.

Victim to show up in court

Frank S. addressed the court on Friday, admitting his involvement with extremist circles in the 1990s. However, he denied ever having been a neo-Nazi himself.

"I am more tolerant than many others," he said on the first day of trial.

According to the defendant, his previous prison term was due to fights with antifascist groups and "political matters." He also described himself as a "rebel with conservative values."

During his address, the defendant did not deny the attack on Reker, adding he would provide his reasons for it at the end of the trial.

If convicted of attempted murder, the alleged attacker could face life in prison. His lawyers, however, claim the stabbing should be classified as grievous bodily harm, which carries a maximum sentence of 10 years.

Cologne mayor Henriette Reker is due to testify in two weeks.