Mom believes son poisoned by highly toxic heavy metal thallium

A Minneapolis family is desperately seeking answers after a 33-year-old man's sudden death, now being investigated as suspicious, which they say appears to have been caused by exposure to the highly toxic heavy metal thallium.

Thallium was used to kill rodents until that use was banned in the U.S. in the 70s because of safety concerns over accidental exposure to the toxic substance. It is still used in the manufacture of electronics, thermometers and specialized lenses, but it also has a notorious history of being used for murder.

Family members say Cody Ernst, 33, was a gentle giant who had been sober for six months. But they say his life came to an end, just as it appeared to be turning around.