A former personal trainer at the Four Seasons Resort and Club in suburban Dallas has pleaded guilty to threatening to sell a tabloid false information about drug use in an attempt to extort money from the wife of TV celebrity psychologist Dr. Phil McGraw, prosecutors said Tuesday.

Randall Robinson, 38, of Lewisville, Tex., pleaded guilty earlier this month to one count of communicating a threat in interstate commerce, U.S. Atty. Jane Boyle said in a news release.

Robinson admitted that he telephoned Robin McGraw on Nov. 17 and left a message threatening to falsely tell the National Enquirer that he had given her speed and methamphetamine while he was her personal trainer, Boyle said. He demanded a $7,500 loan for his silence.

He also admitted that he repeated his demand in a follow-up phone call two days later.

Robinson hoped to exploit Phil McGraw’s celebrity, Boyle said. According to court documents, Robinson worked as Robin McGraw’s fitness trainer in 2001.

Phil McGraw, a Texan who is known as Dr. Phil to millions of viewers, is the resident expert on human behavior on the “Oprah Winfrey Show.” A best-selling author of self-help and relationship advice books, he recently launched his own syndicated show.

A five-count indictment returned June 4 by a federal grand jury in Dallas also charged Robinson with mail fraud, alleging that he mailed false billings for services that he did not perform when he was working as a personal trainer at the Four Seasons Resort and Club in Irving, Texas.

Robinson’s defense attorney, Carlton McLarty, was out of town and unavailable for comment Tuesday.

Robinson faces a maximum sentence of two years in prison and a $250,000 fine. Sentencing is Dec. 13.