Police in Japan are investigating whether a serial poisoner is responsible for killing as many as 48 elderly patients by injecting disinfectant into their intravenous drips.

Suspicions began after an autopsy showed two elderly patients had been poisoned in Oguchi Hospital, Yokohama.

Sozo Nishikawa and Nobuo Yamaki, both 88, died on 18 and 20 September respectively after having a drip administered.

Investigators found 10 unused intravenous drip bags with small holes in their rubber seals on the fourth floor of the hospital, where the two elderly patients had died, The Japan Times reports.

Police believe the suspect may be an insider with medical knowledge.

They are now also investigating the deaths of 46 elderly patients since July, who were being treated on the same floor as the two deceased men.

Hospital staff told the newspaper there had been no outbreaks of infection which could account for the deaths.

The two patients died around a lightly staffed three-day public holiday. The entrance to the hospital was locked and guarded at night.

Last month, a staff member's lips became blistered after they consumed a drink that may have been laced with bleach, The Japan Times said in another report.

It is unknown whether the incidents are related.

The investigation comes two months after the killing of 19 people at a facility for the disabled near Tokyo. </s> Police said on Monday that a German nurse who was jailed for murdering two patients, is suspected of killing 84 others.

Oldenburg police chief Johann Kuehme told journalists that the additional murder cases arose after investigations dug up the remains of 134 people with links to the man.

Kuehme said the number of victims could be even higher as some of the deceased had been cremated.

If convicted, the man identified only as Niels H. under reporting rules, would be one of Germany’s most prolific serial killers.

German broadcaster, NDR, said in past hearings, he admitted deliberately injecting patients at two clinics in northern Germany with deadly drugs and then trying to revive them in order to play the hero.

The man, now aged 40, was convicted in the northern city of Oldenburg of two charges of attempted murder and two counts of murder in 2015.(Reuters/NAN) </s> FRANKFURT, Aug 28 (Reuters) - A German nurse jailed for murdering two patients is suspected of killing at least 84 other people, police said on Monday.

The man, identified only as Niels H. under reporting rules, has "confessed in many of those cases", a police statement said, but could not remember all the details of his actions. If confirmed, the death toll would be among the worst ever compiled by a German serial killer.

In past hearings, Niels H. admitted deliberately injecting patients at two clinics in northern Germany with deadly drugs and then trying to revive them in order to play the hero, German broadcaster NDR said.

He was convicted of two charges of attempted murder and two counts of murder by an Oldenburg court in 2015.

Police said on Monday that they had investigated additional deaths at hospitals in the northern German cities of Oldenburg and Delmenhorst after exhuming the remains of 134 people with links to Niels H.

They said he had used five different drugs on the patients, including alkaloid ajmaline and arrhythmia drug sotalol, between 1999 and 2005.

Toxicological reports for 41 people have not been completed, which means the number of victims could rise, police said.

Prosecutors have also charged six people who worked with Niels H. at the Delmenhorst hospital on suspicion of failing to stop the killing even though they were aware of it.

Ten years ago, a German nurse was convicted of killing 28 elderly patients. He said he gave them lethal injections because he felt sorry for them. He was sentenced to life in prison.

In Britain, Dr. Harold Shipman was believed to have killed as many as 250 people, most of them elderly and middle-aged women who were his patients. Known as Dr. Death, Shipman was sentenced to 15 life terms in 2000; he died prison in 2004, apparently a suicide. (Reporting by Maria Sheahan; Editing by Larry King) </s> More than a quarter of Japan's population is aged 65 and above, putting a strain on medical and nursing facilities, where long hours and low pay discourage workers, a problem the government has vowed to tackle.

September's deaths follow the stabbing deaths of 19 residents of a home for the disabled in July, and the indictment of a former worker of a nursing home for killing three residents by throwing them off a balcony.

Police have said autopsies showed poisoning as the cause of death of two 88-year-old male patients on Sept. 18 and 20. Media said the men died as they received intravenous drip injections on the fourth floor of a Yokohama hospital.

A task force has been set up to conduct an investigation, police in the Kanegawa prefecture, south of the capital, said in a statement on Sept. 23.

Police believe someone probably injected disinfectant into their drip feed bags, media said, adding that no arrest had been made, and police were checking if the deaths could be linked to others on the same floor.

Replying to a query from Reuters whether police had told the hospital of autopsy findings that a surfactant, widely used in disinfectant and cleaning products, was present in the bodies, Yuki Uehara, a lawyer for the hospital, said, "Yes".

He did not elaborate.

From July until Sept. 20, as many as 46 other patients died on the same floor, or an average of 18 a month. That outstrips the monthly average of eight deaths on that floor during the 12 months to June, Uehara said.

He added, however, that the number of seriously ill patients in the hospital had risen from April onwards, which could partially explain the increase in the number of deaths.

Japan's social security system is creaking as the numbers of old people grow. Health ministry data show that abuse of elderly patients by nursing facility workers rose 36 percent in the year ending March 2015, to hit a record of 300 cases.
Authorities arrest a Japanese man for killing as many as 48 elderly patients at the Oguchi Hospital in Yokohama.