A German doctor who killed patients with his bizarre methods — including using lemon juice to disinfect operation wounds and removing healthy organs without cause or permission — was jailed for four years Monday.

The prison term, in a minimum security facility, would be followed by a four-year ban on Arnold Pier practicing medicine, a Monchengladbach court ruled.

The 54-year-old doctor, and owner of a private clinic, was sentenced on two counts of negligent homicide and 21 counts of bodily harm, news website The Local reported.

Four patients did not survive his treatment, which the court said was akin to "flying blind."

In some cases he removed organs without permission, subjected a patient to unnecessary chemotherapy, and sewed a man's thumbs back on after an accidental amputation without specialist care — which led to the digits rotting and having to be removed.

"How he imagined he could simply sew the thumbs back on is hard to grasp," Judge Lothar Beckers said.

The court acknowledged that Piers had not acted out of malice, but had made mistakes in an attempt to help patients while he was overwhelmed. It also said the sentence would have been significantly longer if Piers had not confessed.

Click here to read more.