The mysterious spate of vape-related deaths and illnesses continues to grow, confounding experts. Here's what officials knew and when.

The first vape-related death is reported in Illinois.

The person, who has remained unnamed, was hospitalized with severe breathing difficulties, according to officials. He was reportedly using e-cigarettes to consume nicotine.

Oregon's Health Authority says it is actively investigating the death of an individual with a severe respiratory illness following the use of an e-cigarette.

While officials have not yet determined the root cause of the middle-aged person's illness, he had reportedly fallen ill after vaporizing marijuana oil purchased at a legal cannabis dispensary, reports The Associated Press.

Dr. Scott Gottlieb, the former FDA commissioner, writes an editorial in The Washington Post urging federal officials to take action in investigating the causes of these illnesses and deaths.

"Bright lines must be drawn between less-harmful ingredients and those that cause undue risk. That would arm regulators with the information to crack down on illegal and dangerous vape juices. It's also time to end the political ambivalence that allows THC and CBD to evade oversight," Gottlieb wrote.

Indiana health officials confirm a third vape-related death. Shortly afterward, officials in Minnesota confirm a fourth, and then a fifth in California.

Like the other deaths, officials have yet to determine a root cause. However, the 65-year old Minnesota man had a history of lung disease. He fell ill after vaping an "illicit" THC product, The New York Times reports.

Acting FDA Chief Ned Sharpless says "Our investigation into the concerning reports of respiratory illness and deaths associated w/ vaping is a top priority for FDA and our federal, state, local health partners. We're working tirelessly to gather and analyze information about these incidents," on Twitter.

Sen. Minority Whip Dick Durbin pushed Sharpless to act quicker in a letter addressed to Sharpless on Friday.