After five days of furlough freedom in Maryland, Marvin Mandel was rudely returned to the reality of prison life Wednesday. He was tossed into detention immediately after arriving at the Eglin Air Force Base prison camp in Florida.

Officials there say it was because he'd been drinking.

Mandel's wife says it was because prison officials are out to get the former governor.

And there was yet another possibility, that Mandel's ever-present pipe was the culprit.

The episode began when Mandel, completing a five-day furlough, arrived at Eglin late Wednesday and failed a routine "balloon test" used to detect alcohol on the breath, according to prison officials. One of the conditions of any prison furlough, they said, is abstinence from alcohol. Because of the test results, Mandel was placed in a cell by himself for one night, away from his dormitory cubicle.

A short time later, Jeanne Mandel called reporters from her Annapolis home to say that the former governor had been put in solitary confinement by officials angered because he had given press interviews during his furlough. She refused to believe he had been drinking. "He's not going to jeopardize himself by doing something like that."

But yesterday a Maryland State Police alcohol testing expert offered another possible explanation for the controversy. He said the balloon test can be "unreliable" in determining whether a person has been drinking, so the state does not use it. Tobacco smoke, for instance, could make the crystals in the device turn from white to green, an indication that the breath contains alcohol, said Sgt. Frederick Kirckhoff, who works in the department's chemical tests for alcohol unit.

"I blew pipe smoke into one [of the devices]," said Kirckhoff, a pipe smoker himself. "And it did change colors."

Whether Mandel was smoking his trusty Meerschaum pipe when he walked into prison, no one has said.

But prison officials did say yesterday that the balloon test is a "standardized test used on motorists," and that it was administered to Mandel in the same way as other returning inmates.

They denied Jeanne Mandel's contention that her husband was being punished for talking to the press. "We have no grudge against Mandel," said one source. "In fact, we were delighted when he told the papers that this is no country club down here but a prison."

Mandel, who has been ordered by the U.S. Parole Commission to serve, essentially, his entire term, could face sanctions from the Bureau of Prisons because of this episode. He has served 14 months of his sentence for political corruption, and is scheduled to be paroled next May.

A hearing was scheduled today for Mandel before officials in his prison unit to determine if he had been drinking during furlough. Mandel will have an opportunity to defend himself against the charge, according to a Bureau of Prisons spokesman. If he is found to have violated furlough regulations, he could face sanctions ranging from extra duty to loss of "good time" days, which are used to shorten his sentence. Mandel has earned the maximum number of days possible.