Two men have been found guilty and sentenced to prison by a German court, for a 2018 acid attack on a top executive at the energy firm Innogy.

The two attackers ambushed the businessman, Bernhard Günther, near his private home in a suburb of Dusseldorf, and doused him with highly concentrated sulphuric acid in March 2018.

Günther had just returned from his Sunday jog, and had brought fresh bread rolls with him after a stop at the bakery.

Günther was seriously injured in the attack, and his eyelids and parts of his facial skin had to be transplanted.

A regional court in Wuppertal on Monday convicted a 37-year-old man of acting as an accomplice in the attack, and sentenced him to 11 years in prison.

The alleged main attacker, a Belgian citizen, was previously convicted as well and sentenced to 12 years in prison.

The presiding judge in the case, Klaus Blume, said on Monday that it was clear the attackers hoped to blind Günther.

The judge noted that when a mobile phone was analyzed, a deleted chat between the two culprits could be restored, and the 37-year-old defendant, an amateur wrestler, had also displayed conspicuous behaviour and deleted his phone number two days after the crime.

The judge conceded, however, that the identity of whoever ordered the attack remains unknown.

“We are happy about the clear conviction,” said Günther after the end of the trial. “This is not the end of our journey. We are still doing everything we can to identify the people behind the crime and who ordered it.”

Günther said the trials provided evidence that “we have been right in our hypothesis that the client comes from my professional environment.”

At the time, Günther was head of finance at the energy company Innogy, which was taken over by the Eon Group a few days after the attack. Today he is an executive at Finnish energy supplier Fortum.

Günther has sought for years to identify the perpetrators and find out who ordered the attack. He suspects a professional conspiracy may have led to the attack.

An anonymous tipster collected a reward of almost €200,000 ($215,000) put up for information that would solve the case.

Defence lawyers in the case had criticized the payment of the reward and argued, that Günther’s statements about the case have not always been consistent.

The court rejected last-minute efforts by the defence to present evidence they claimed would show the man was in Belgrade at the time of the attack.