Updated

German prosecutors have attributed one more murder to a former nurse accused of killing dozens of patients at two hospitals, bringing to 98 the number of slayings he is expected to face trial for later this year.

Niels Hoegel is already serving a life sentence for two murders. He was charged earlier this year with killing 97 more patients over several years at the hospitals in northwestern Germany. His trial is scheduled to open Oct. 30 in Oldenburg.

News agency dpa reported that prosecutors said Thursday they are accusing Hoegel of one more killing after medical experts found traces of a cardiac drug in samples from one patient but erroneously told investigators the result was negative.

The state court will decide whether to add the case to the indictment.