Germany will not prosecute a former Nazi SS soldier who allegedly helped kill more than 300 people in Italy during World War II because he has dementia and is unfit to stand trial, prosecutors said on Thursday.

Hamburg state prosecutors have ended their investigation into the unnamed 93-year-old former company commander in the 16th SS Panzergrenadier Division, their office said in a statement.

The man is alleged to have been involved in a massacre in northern Italy on Aug. 12, 1944. SS troops on anti-partisan operations surrounded the village of Sant'Anna di Stazzema in Tuscany and killed hundreds of people, including many women and children.

"The assessment of the extensive file material had led to the conclusion that the accused — had he been fit to stand trial — would have in all probability been charged with 342 cases of cruel murder with reprehensible motives," the prosecutors office said in a statement.

But psychiatric and neurological examinations of the man have shown that he suffers from very advanced dementia, so he would not be able to stand trial under the terms of Germany's constitution.

The number of people who can be prosecuted for Nazi war crimes is dwindling as elderly suspects die.

In April, a German court started the trial of a 93-year-old former bookkeeper at the Auschwitz concentration camp accused of assisting in the mass murder of Jews. It could be one of Germany's last big Holocaust trials.