Former IndyCar and IMSA driver Bill Whittington will return to prison after being sentenced to an 18-month stay for tax fraud.

The 68-year-old agreed to a plea deal in May for filing a false tax form in 2010 where he under-reported $390,000 in income. Whittington also admitted to using the family-owned Springs Resort & Spa in Pagosa Springs, Colorado, to cover personal expenses from 2010 through 2012 that led to “underreporting his income by more than $900,000 and not paying more than $360,000 in taxes,” according to the United States Department of Justice.

The US DOJ also found that “from 2003 to 2010, Whittington used two offshore bank accounts in Liechtenstein to generate approximately $9.7 million in investment income. Whittington did not pay taxes on this income, resulting in a tax loss of at least $1.5 million. In total, Whittington did not pay at least $1.8 million in taxes owed to the Internal Revenue Service.”

On Tuesday, Whittington was convicted of tax-related improprieties for a second time, with the first coming in 1986 when he was also found guilty of drug smuggling.

As part of IMSA’s notorious mid-1980s group of drug traffickers that included Whittington and his brother Don, Randy Lanier, along with John Paul Sr. and Jr., the group became the faces of a series jokingly referred to as the “International Marijuana Smugglers Association.”

Whittington was sentenced to 15 years in prison starting in 1987, and was joined by Don, who was given seven years for money laundering. Whittington’s friend and co-driver Lanier, who received a life sentence, was paroled earlier this decade. The Pauls, who served differing sentences for their own smuggling operation, have gone in separate directions.

John Paul Jr. returned to racing after his five-year prison stay and found success in the Indy Racing League and IMSA before battling Huntington’s disease in recent years. His father served 15 years for drug-related crimes and attempted murder, attempted to escape prison, served his time, and disappeared in 2001 while being sought for questioning on other matters.

As part of his recent plea, Whittington also agreed to pay a fine of $1.8 million in restitution for the monies owed to the IRS.