WASHINGTON—Peter W. Smith, a Republican political activist and financier from Chicago who mounted an effort to obtain former Secretary of State Hillary Clinton’s emails from Russian hackers, died on May 14 after asphyxiating himself in a hotel room in Rochester, Minn., according to local authorities. He was 81 years old.

Mr. Smith’s body was found by a hotel clerk in the Aspen Suites hotel, located across the street from the Mayo Clinic, according to a Rochester Police Department report. An associate of Mr. Smith said that he had recently visited the clinic. A representative for the facility wouldn’t confirm if Mr. Smith was a patient.

Mr. Smith died about 10 days after an interview with The Wall Street Journal in which he recounted his attempts to acquire what he believed were thousands of emails stolen from Mrs. Clinton’s private email server. He implied that Lt. Gen. Michael Flynn, then serving as the senior national security adviser to presidential candidate Donald Trump, was aware of his efforts.

Mr. Smith’s attempts to obtain what he believed would be politically damaging emails marked the first potential evidence of coordination between members of the Trump campaign and Russian hackers, a central issue in probes by Congress and the Federal Bureau of Investigation into Russian meddling in the 2016 election.

When the Journal reported on Mr. Smith’s efforts last month, it wasn’t clear how he died. His obituary listed no cause of death, officials in the town where he lived didn’t release information, and messages left at Mr. Smith’s home went unanswered.