(Bloomberg) -- A Houston lawyer’s death a day before he was to go on trial for allegedly helping billionaire Robert F. Smith evade taxes was a suicide, according to a medical examiner’s report. 

Carlos Kepke died of a self-inflicted gunshot wound to the head, in a bedroom at his home on Sunday, according to the website of the Harris County Institute of Forensic Sciences. 

Kepke, who was 83, was scheduled to begin his trial Monday in San Francisco federal court on charges of conspiring to defraud the US Internal Revenue Service and aiding and abetting the filing of false tax returns by Smith, founder of Vista Equity Partners. Smith, 59, was expected to testify against Kepke. He avoided prosecution after admitting in 2020 he evaded taxes and agreeing to cooperate with the government.

The Kepke trial would have been the coda in a multi-year US investigation.

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Kepke’s lawyers and a spokesperson for Smith didn’t immediately respond to requests for comment on the medical examiner’s ruling.  

“Carlos always maintained that he was innocent of these charges, and we were prepared to prove that at trial,” Kepke attorney Richard Strassberg said in an interview Monday. 

Kepke had also worked for the family of billionaire Robert Brockman. Brockman was charged two years ago in the largest individual tax fraud case in US history. A software entrepreneur and original investor in Vista, he died in August before his trial. He was 81 and had been suffering from dementia.

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The judge is expected to dismiss the case after the Justice Department files a formal request. The department declined to comment.

A graduate of the University of Texas law school, Kepke advised high-net-worth clients at a prominent Houston firm specializing in tax law before setting up his own practice in 1992. He focused on “the use of foreign structures for United States tax savings and/or asset protection,” according to his website. 

He had extensive health problems and had suffered two heart attacks.

The case is US v. Kepke, 21-cr-00155, US District Court, Northern District of California (San Francisco).

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(Updates with background on Kepke and the US investigation.)

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