Several security guards at the District’s federal courthouse have landed in foul territory for accepting free baseballs autographed by superstar pitcher Roger Clemens shortly after a judge last month declared a mistrial in his perjury prosecution.

The U.S. Marshals Service confirmed Tuesday that there is an investigation into why and how six signed balls were sent to a guard by someone on Clemens’ defense team. That guard apparently passed the balls along to four or five other officers, the Marshals Service said.

The guards, who work for a private contracting firm, are not permitted to accept gifts from defendants. Baseballs signed by Clemens retail between $100 and $400, depending on their condition.

“The investigation is ongoing but preliminary results indicate that up to six baseballs were given to a contracted court security officer and were distributed among four or five other court security officers,” the Marshals Service said in a statement issued in response to questions by The Washington Post.

The guards work for Inter-Con Security, a California-based firm that provides guards at the U.S. District Court in the 300 block of Constitution Avenue NW. The contract is worth about $5.2 million a year, the Marshals Service said.

A spokesman for Inter-Con could not be reached.The Marshals Service, which ovesees courthouse security, last week asked Inter-Con to investigate the matter and submit a report, according to Marshals spokeswoman Lynzey Donahue.

Depending on the outcome of the investigation, the guards could face a range of disciplines that includes dismissal, according to sources familiar with the probe. The guards’ identities could not be determined.

Clemens did not appear to receive any special treatment from the guards during his trial, which started early last month. He entered the courthouse like anyone else, ate in the cafeteria and left by public entrances. For security reasons and to prevent the disruption of other courthouse business, the guards helped shepherd Clemens past a battalion of reporters and photographers as he left the courthouse after the mistrial was declared on July 14.

The balls may have been a “thank you” gift from Clemens’ defense team for such help, according to the sources familiar with the investigation. Rusty Hardin, Clemens’ lead defense lawyer, declined to comment.

Clemens is charged with lying to Congress in 2008 when he denied ever having taken performance-enhancing drugs. Just two days into testimony last month, Clemens’ high-profile perjury trial came unglued when federal prosecutors blundered and presented barred evidence to the jury. U.S. District Judge Reggie B. Walton declared a mistrial and is now weighing legal arguments about whether federal prosecutors should get another crack at the 11-time All Star.

The mistrial was an embarrassment for the Justice Department, and the prosecutorial error clearly irked Walton.

Lawyers not associated with the case said that providing such gifts was not a smart move. “It would have been more prudent to wait until the case was completely over,” said Steven Levin, a former federal prosecutor and criminal defense attorney. “I don’t know what the rush was to do it.”

The baseball gift is not likely to please the judge. Walton and federal prosecutors declined to comment on the baseball matter.

Chief U.S. District Judge Royce C. Lamberth said the allegations “involve potential misconduct” by the security officers. Lamberth declined to comment further, saying “we don’t know all the facts yet.”

This story has been updated.