The concentration of arsenic needed to kill someone would not be found in cleaning solutions or other common household products, an expert said.

“It’s not the easiest way to kill someone,” said Toby Rossman, a professor of environmental medicine at New York University.

Donald Alger, a professor of chemistry at California State University at Chico, said it could take as little as 70 milligrams to kill. That would amount to a pinch of pure arsenic, he said.

State police are continuing their investigation into an arsenic-related illness that swept through a church in New Sweden, killing a 78-year-old man and sickening a dozen others on Sunday.

Investigators have characterized the incident as “suspicious” and are looking for the source of the arsenic. State Police Lt. Dennis Appleton has said there is no evidence as yet that a crime was committed.

Arsenic occurs in nature as a mineral. In Maine, it’s found in potentially harmful levels in one out of 10 wells in Maine, according to the Department of Human Services.

Arsenic has been used as a poison since the Middle Ages. It’s believed to have killed Napoleon in 1821.

It was considered to be a good choice for killing someone because it was hard to detect and its symptoms – vomiting, diarrhea, abdominal pain – could be confused with many other illnesses.

More than 50 years ago, the hit play and movie “Arsenic and Old Lace” depicted two elderly ladies who put lonely men out of their misery by offering them elderberry wine laced with arsenic.

Investigators are still looking for the source of the arsenic in New Sweden. But they’ve ruled out the well water.

Both Rossman and Alger said the Maine case sounds suspicious.

“Unless someone purposefully dumped something into a water supply, you’re not going to get arsenic levels high enough to just kill people,” Alger said.