A middle-age Oregon resident who died from lung disease tied to vaping bought cannabis oil from two marijuana retail stores and investigators are now trying to find leftover product to analyze it, state health officials said Thursday.

It’s unclear if the person vaped products from one or both of the stores, said Oregon Health Authority spokesman Jonathan Modie. Nor do health officials know if the person altered the THC liquid or mixed it with a home-made product, Modie said.

Health investigators are trying to track the oil to figure out if or how it led to the resident’s death in July. Officials wouldn’t identify the stores where the victim shopped.

The Oregon death is one of just two in the country connected to e-cigarettes amid an outbreak of 215 cases of severe lung disease in 25 states. Many cases have been linked to vaping oils that contain THC, the psychoactive component of marijuana that gives people a high.

The agency learned of the death in August, at least 19 days after the person died. Investigators with the Oregon Health Authority believe the oils the victim used can still be found.

“What is believed to be connected to this case is still out there,” Modie said. “We’re trying to retrieve it.”

Medical experts don’t know what’s causing the illnesses, with theories ranging from bootleg products to low-quality e-cigarette cartridges to Vitamin E oils. A sample of the product used by the Oregon victim could help both local and federal investigators better understand the outbreak.

If the health authority can get samples of the marijuana oil, investigators will take pictures, then send it to the U.S. Food and Drug Administration for analysis. If the tests reveal hazardous components in a specific product, the agency will warn the public against using that product, Modie said.

The lung disease striking people usually starts with a cough, difficulty breathing and chest pain, said state public health expert Ann Thomas. Some patients also report nausea, fatigue and diarrhea. People will sometimes have such a tough time breathing that they’ll have to get oxygen treatment at a hospital. In extreme cases, patients will get oxygen with the help of a ventilator.

Modie said the agency has no plans at the moment to pull specific marijuana products off shelves. At this juncture, health officials just don’t know enough about what caused the Oregon victim’s lung illness.

Nor can the agency give specific advice for people who vape but want to avoid getting ill.

“The best advice we can give people is to not vape,” Modie said.