A University of Colorado Boulder student found dead in east Boulder after going missing in March died by suicide, according to the Boulder County Coroner’s Office.

Mikhail “Misha” Solok, 19, of Aurora, was found dead by a passerby April 16 on the east side of South Boulder Creek in the area of 1800 South Flatiron Court.

According to an autopsy report written by Dr. Daniel Lingamfelter, Solok died of “methylphenidate intoxication in the setting of drowning.”

Methylphenidate, sold under the brand name Ritalin, is used to treat attention deficit hyperactivity disorder and narcolepsy. According to the report, Solok had a “lethal” amount of the drug in his system, with nine intact capsules and partially digested capsule residue found in his stomach.

The report notes Solok had left a note in his bedroom, had struggled with depression and had made suicidal statements to others.

Solok had no physical injuries, according to the report.

While the report lists only that Solok was declared dead on April 16, the report noted there was some decomposition, and police said the body had likely been in the creek “for some time.”

Solok was last seen on March 15, and police searched for him for a month before his body was discovered.

Solok was a political science major at CU Boulder.