Niels Hogel, a former German nurse, admitted on Tuesday to murdering 100 patients at hospitals in the country between 1999 and 2005.
Detectives say the 41-year-old administered fatal doses of medication to the people in his care, seeking to impress colleagues by trying to revive the patients he had attacked.
Euronews takes a look at other cases around the world where doctors and nurses have killed their patients.
UK: Harold Shipman
British doctor Harold Shipman was convicted in 2000 of killing 15 elderly patients under his care with lethal injections of morphine.
However, a public inquiry into his crimes found that he killed at least 250 patients between 1971 and 1998.
Shipman, known as “Doctor Death”, committed suicide by hanging himself a day before his 58th birthday in 2004.
UK: Colin Norris
Scottish nurse Colin Norris was jailed for life in 2008 after being found guilty of murdering four elderly patients and attempting to kill a fifth at hospitals in Leeds, northern England.
Norris was said to have injected his victims with lethal doses of insulin in 2002.
Police said they believed that if Norris hadn’t been caught he could have continued killing patients.
France: Marcel Petiot
French doctor Marcel Petiot was beheaded in 1946, aged 49, after 23 bodies were found in his Paris home during World War II.
Petiot was suspected of killing 60 people but the true number is unknown.
The bodies were discovered after a fire brigade went to Petiot’s home to respond to complaints from neighbours to police of a foul smell and large amounts of smoke coming from a chimney.
The human remains were found in the basement and in the fire.
US: Charles Cullen
Charles Cullen confessed to killing up to 40 patients during his 16-year career as a nurse in New Jersey, Pennsylvania.
It’s estimated that Cullen may be responsible for some 400 deaths by injecting them with lethal medication.
He was arrested in 2003, aged 43, for one count of murder and one count of attempted murder but told detectives he’d been responsible for killing more.
He was sentenced to 18 consecutive life sentences and isn’t due for parole until 2403.