JACKSON, Miss. (AP) _ A former highway commissioner was sentenced Wednesday for extortion after being caught up in a corruption investigation that also led to the resignation of another man on the three-member commission.

Former Southern District Highway Commissioner Bob Joiner, 59, was sentenced to six years in prison on the federal extortion charge and received a five- year suspended sentence on a tax evasion count.

U.S. District Judge Tom S. Lee told Joiner a pre-sentencing report showed ''you blatantly solicited kickbacks from contractors'' and that ''the only redeeming factor in your behalf is that you have cooperated with the prosecutor.''

Joiner, of Waynesboro, was indicted in December 1987 on 11 federal counts following a federal probe with cooperation from then-state Auditor Ray Mabus, whose office had been investigating the state Highway Department since 1985.

Nine charges were dismissed when Joiner cooperated with investigators.

Joiner was accused of extorting $238,156 from four construction contractors and of underestimating his income tax from 1981-84.

He could have been sentenced to up to 25 years. In recommending the six- year sentence, Assistant U.S. Attorney Ruth Harris noted that Joiner had participated in a federal investigation that led to obstruction of justice charges against former Marion County Supervisor Sim Ed Moree.

Moree was sentenced Tuesday to almost seven years in prison.

Harris said Joiner also participated in the investigation that led to a filing of court documents in December implicating then-Central District Highway Commissioner Sam Waggoner. He resigned later in the month.

Waggoner had been scheduled to enter a guilty plea to the charges Monday, but his court appearance was delayed because of an ice storm that hit the state. It has not been rescheduled.

Joiner first took office in 1980 and had begun serving a third term in January 1988. He resigned last May. A special election was held in July to replace Joiner and a special election next month will fill the remaining three years in Waggoner's term.

The commission directs state road building in Mississippi and oversees the 3,200-employee Highway Department.