The Assistant Special Agent in Charge for the president's Secret Service detail believed to be involved in a long-term affair with a Mexican woman committed suicide a day after failing a national security polygraph and being stripped of his clearances and access, according to sources. 

Rafael Prieto, a supervisor on President Obama's Secret Service detail, was found dead last weekend in the passenger side seat of his roommate's car in the garage of their Washington D.C. residence, clutching a photograph of his two children, multiple sources told FoxNews.com. The suicide came a day after a Do Not Admit email sent agency-wide for Prieto was sent by the Security Clearance Division. 

A senior law enforcement official confirmed Prieto's clearance had been pulled, calling it "standard practice" for an employee going through an "administrative process." The official said the investigation "was related to clarifying a long-term ongoing relationship with a foreign national." 

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