Gang Charges in Denny Beating Case to Be Dropped : Riots: Probe of police officer who testified forces move. Defendants’ bail and possible sentence could be reduced.

Prosecutors in the case of three men accused of beating truck driver Reginald O. Denny are being forced to drop special gang allegations against the defendants because the Los Angeles police officer who supplied the evidence is under administrative investigation, according to a letter from prosecutors to the judge.

Dropping the so-called gang enhancement reduces the minimum sentence that each defendant would face if convicted and could affect motions to reduce their bail. In addition, defense lawyers maintain that dropping the special allegations could undercut the prosecution’s charge that the three men acted as part of a gang when they beat Denny.

“The district attorney’s office has just received information from the Los Angeles Police Department that Officer Michael McMahan is under administrative investigation,” according to the letter, sent to Superior Court Judge John W. Ouderkirk on Monday and obtained by The Times on Wednesday. “Had the LAPD investigators on the case or the district attorney’s office been aware of this investigation at the time of the preliminary hearing, Officer McMahan would not have been called as a witness.”

Instead, McMahan was called and testified that two of three defendants--Antoine Eugene Miller and Damian Monroe Williams--were affiliated with the Eight-Tray Crips, a notorious South-Central Los Angeles street gang. McMahan did not allege that the third defendant, Henry Keith Watson, was a member or associate of the gang, but Watson also was charged with the gang enhancements.

“The whole focus of their case has been that these three were gang members acting in concert,” said lawyer J. Patrick Maginnis, who represents Miller. “This really gives the prosecution a black eye.”

Sandi Gibbons, a spokeswoman for the district attorney’s office, said officials would have no comment on the investigation of McMahan because it is a personnel matter and is still under review.

Gibbons acknowledged that the special enhancement would be dropped and said that could reduce the minimum sentence for the defendants. But she added that if the three men are convicted of the most serious charges against them they still face possible life sentences.

“We feel that we have a strong case,” Gibbons said. “We always have felt we have a strong case, and we intend to prosecute it vigorously.”

Lawyers for the other two defendants said that without the gang allegations, the attack on Denny is more accurately characterized as an assault, rather than as an attempted murder or torture. Assault carries much less severe penalties than murder or torture.

Each of the three suspects is charged with attempted murder, torture, aggravated mayhem and robbery in the Denny beating, as well as with lesser charges for alleged attacks on other motorists. All the attacks occurred near Florence and Normandie avenues during the opening hours of the Los Angeles riots, and several were broadcast live on television.

If convicted on only the attempted murder charge, all three men could face life in prison. In addition, the gang enhancement would have forced them to be locked up for at least 15 years before they could be considered for parole. Without the enhancement, they could be paroled much earlier, though how soon would depend on which charges, if any, they were found guilty of.

McMahan could not be reached for comment Wednesday. A police spokesman said the department would not have any immediate comment.

It was not clear from the letter what the investigation of McMahan involves.

In addition to setting minimum sentences, the gang allegation has been an important part of the prosecution’s theory of its case, particularly against Miller. Prosecutors and police officers acknowledge that Miller did not hit Denny during the attack, but he has been charged with aiding and abetting the crime. They say that Miller did so in part out of loyalty to the Eight-Tray Crips.

In the letter to Ouderkirk, which is signed by Assistant Dist. Atty. Frank E. Sundstedt on behalf of new Los Angeles County Dist. Atty. Gilbert Garcetti, prosecutors indicate that they will move to strike the gang enhancements during their next court appearance. That is scheduled for Friday when Ouderkirk will hear motions to reduce the bail for Miller and Williams.

Maginnis and lawyer Edi M.O. Faal, who represents Williams, said the latest revelation would bolster their charge that the bail amount is excessive.

“I think this will have significant impact on the bail motion,” Faal said. “A major element of the prosecution’s case is that these men were doing this for gangs. Now that element is gone.”

The bail set for the three defendants has been a point of contention since their arrests. Each defendant’s bail is at least $500,000, and their supporters argue that the amount is unfairly high--especially in contrast to the $5,000 bail set for the four police officers charged with beating Rodney G. King.