The official autopsy report on Lexxi T. Sironen, who was found dead in the Kennebec River in Waterville on Sept. 6, shows that she was impaired by alcohol and had narcotics and stimulants in her system.

Sironen, 43, was found dead by a Brookfield Power Facility worker who noticed a body floating in the reservoir area near the dam next to the Hathaway Creative Center on Water Street.

The full autopsy report, obtained by the Morning Sentinel under a public records request, says the cause of death is “undetermined” because the body was recovered after “prolonged submersion in the water.” It is unclear how long the period of time has to be to be considered a prolonged submersion by the Medical Examiner’s Office.

Mark Flomenbaum, chief medical examiner who performed the autopsy, says in a note in the report that the “toxicologic findings” may help explain Sironen’s “state of mind around the time of death,” though it will not explain how or why her body was found in the river. As a result of those findings, Waterville police closed the investigation into Sironen’s death.

Sironen had 91 milligrams per deciliter of ethanol, or alcohol, in her system, which has a whole blood equivalent of 0.080 grams per 100 milliliters, which is the limit for impairment, according to a toxicology report completed by NMS Labs in Pennsylvania that’s attached to the autopsy report.

Test results also showed 65 nanograms per milliliter of methamphetamine, an illegal stimulant drug that can cause hallucinations, irrational reactions and aggressive behavior, according to the report. There are two isomeric forms of methamphetamine, one of which is the abused substance, but the report did not differentiate which isomeric form was found in Sironen.

Also found were 69 nanograms per milliliter of methylphenidate, or ritalin, a stimulant similar to amphetamine that can either be abused or used to treat disorders.

Sironen’s system also had 9.2 nanograms per milliliter of buprenorphine, a synthetic derivative of an opioid that can be used to treat pain as well as addiction to narcotics and is known to be much more potent than morphine. Buprenorphine is not intended to be mixed with alcohol or illegal drugs.

NMS Labs declined to comment on the findings and referred back to the state Medical Examiner’s Office, which did not return an email or phone calls seeking clarification and comments on the full report.

The report concludes that drowning is the most likely cause of death, but with the caveat that the prolonged exposure to water means it cannot say for sure if Sironen was alive or dead when she entered the water. Drowning is a “diagnosis of exclusion,” the report says, which means it was determined by elimination so it is not the definite answer. No fractures or signs of trauma were found elsewhere on her body.

Sironen was found wearing pants, underwear, one sock and one shoe. The report says that because she was dressed, if drowning was the cause of death, then there is little to indicate how Sironen entered the water — it could have been by force, accidentally or intentionally.

While the cause and manner of death have been deemed undetermined, the conclusion can be amended if “significant” new information is discovered.

According to a family member, Sironen had lived in Skowhegan and had been visiting friends in Waterville the week before her death.

Friends of Sironen said she was generous and would “do anything for anybody.” Chelsea Letourneau said Sironen, whom she knew for eight years, would give money to friends in need and loved her life.

Madeline St. Amour — 861-9239

mstamour@centralmaine.com

Twitter: @madelinestamour