CHICAGO — Theodore Hilk — the MIT graduate who was found dead in a Streeterville apartment that contained explosive materials last March — died of lidocaine toxicity, newly released autopsy records show.

Lidocaine, according to records from the Cook County Medical examiner’s office, is used to treat heart arrhythmia, but “is also used as a cutting agent in some drugs of abuse.”

Hilk, 30, was found dead in his apartment at 240 E. Illinois St. in late March after his parents could not make contact with him for several days.

During a search of his cluttered home, police found two pipe bombs and other explosive materials, prompting an evacuation of the building.

It remains unclear when Hilk died, but his toxicology report shows that he had alcohol and amphetamine in his system at the time of his death.

Additionally, according to the medical examiner’s office, Hilk tested positive for hydroxychloroquine — a drug used to treat malaria that former President Donald Trump suggested could be used to cure COVID-19.

Hilk also suffered from anxiety brought on by the COVID-19 pandemic, his father told detectives.

The management at Hilk’s building was alerted to his suspicious behavior six months before he was found dead, records show.

In detectives’ notes contained in his autopsy file, it was revealed that a window washer contacted the building’s management in October 2020 after he noticed “multiple propane tanks” inside Hilk’s residence.

“Hilk was informed of building policy against storing such items in his unit and [was] ordered to remove them,” a detective wrote.

Two days later, the building’s management inspected Hilk’s unit and the propane tanks were gone.