A former FBI agent and his wife have been sentenced to years in prison for an investment scheme that used his law enforcement background to swindle their victims, authorities said.

John Robert "Bob" Graves, 52, and Sara Turberville Graves, 44, both of Fredericksburg, were convicted of conspiracy, mail fraud and four counts of wire fraud in April. John Graves also was convicted of investment adviser fraud and lying to the FBI.

John Graves was sentenced to 11 years behind bars on Tuesday. Sara Graves received three years.

Prosecutors said that John Graves, who last worked for the FBI in Washington in 1999, used his position as a former agent to gain the trust of his clients for his investment firm that he started in 2003. He sought older clients, knowing "from his FBI experience that elderly victims were more susceptible to scams," prosecutors said in court documents.

Sara Graves also worked at the investment firm, and the couple ripped off $1.3 million from 11 victims to pay off personal debt and to fund a rich lifestyle and a time share.

"It's despicable," U.S. Attorney Neil MacBride said.

Christine Taugher of Fairfax County testified that she lost her family's $580,000 savings to the Graves after her husband died.

"In a matter of hours, we lost everything," she said. "John Graves took away any start in life my husband left for our kids."

She addressed Graves directly: "I feel sorry for your children and the legacy you are leaving."

Another couple wrote to the court that they struggle to trust people since being victimized by the Graves.

"In addition to the loss of $50,000 in our life savings, our trust and faith in our fellow human beings has been severely tested," they wrote.

In one instance, John Graves took $150,000 from a client and bought a house in his own name without telling the victim what he had done with her money, prosecutors said.

In another instance, he promised to invest a family's inheritance into a real estate venture, but instead transferred the money through his and his wife's personal savings account to pay off his business debts, prosecutors said.

Former FBI profiler and TV crime analyst Clint Van Zandt, a character witness for John Graves, said he believed his friend made bad investments, then tried to make it right by moving investors' money around.

Information from the Associated Press was used in this report.