The images of Bradley fighting vehicles punching holes in the wooden compound of the Branch Davidian sect and of helicopters hovering overhead as the structure burned have become etched in America's collective psyche. The extent and legality of the military involvement in the 51- day siege at the Mount Carmel compound near Waco six years ago is expected to be a focus of upcoming investigations into the fiery end of the siege on April 19, 1993. The bodies of sect leader David Koresh and about 80 of his followers were recovered in the fire's remains. Among questions surrounding the operation is how military personnel, equipment and munitions were used and whether the government had a role in setting the blaze that consumed the compound. At the heart of the questions about military involvement is the Posse Comitatus Act, which prohibits the armed forces from participating in civilian law enforcement operations.

Some issues expected to be examined are:

* The involvement of the Delta Force, an elite, top-secret Army unit established to combat terrorism. Some former government officials say the Delta Force had a greater role in the operation than the FBI acknowledges and, as a result, violated the Posse Comitatus Act.
In a sworn affidavit, a former sergeant first class in Army Special Forces said a noncommissioned officer told him that the Delta Force's "B" Squadron had been ordered to "take down" the Branch Davidians at Mount Carmel.

* Whether federal officials used a 1990 change in the Posse Comitatus Act -- allowing the use of the military in anti-drug operations -- to assist the Bureau of Alcohol, Tobacco and Firearms and the FBI in the Waco siege and assault.
When the ATF asked the military for help in staging its initial raid of the compound on Feb. 28, 1993, military officers said the ATF would have to reimburse the Army for any assistance because there was "no known drug nexus," according to Lt. Col. Lon Walker, an Army liaison to the ATF.
Less than a month later, the ATF added "drug activity" to the matters it was investigating in regard to the Branch Davidians, a move that a congressional report called "deliberately misleading."

* Possible violations of Texas and Alabama state laws prohibiting the use of National Guard personnel and equipment against the Branch Davidians.
Texas law prohibits the use of the Texas National Guard in civilian law enforcement unless there is a clear drug connection. Alabama law says its National Guard force has no authority outside state boundaries.
National Guard personnel and equipment from both states were used at Mount Carmel. A congressional report has determined that those actions were taken without proper authority.

Delta Force

Recent revelations indicate that the Delta Force had a greater presence and a more active role in the final assault on the Branch Davidians than FBI officials have acknowledged. According to at least one account, the Delta Force was there not to advise, but to kill.
Steven Barry, a retired Special Forces sergeant who sometimes trained members of the Delta Force, gave a sworn affidavit to plaintiffs' attorneys in a civil suit brought by families of dead Branch Davidians. The case is scheduled to go to trial in Waco on Oct. 18.
In the affidavit, Barry quoted a friend in the Delta Force as saying the unit set up a tactical operations center during the siege that was staffed by 10 to 20 soldiers.
Barry said another friend in the Delta Force told him that the unit's "B" Squadron had been ordered to "take down" Branch Davidians. Barry said he understood from his experience in the Special Forces that "take down" meant to kill people identified as terrorists.
Barry isn't alone in these allegations.
Former CIA officer Gene Cullen has said in several recent interviews that he learned through casual conversations with Delta Force members that 10 of the unit's commandos were present during the April 19, 1993, assault and may have participated.
Similarly, James B. Francis, commissioner of the Texas Department of Public Safety, said "it is clear" that members of the Delta Force were on the scene. Initial reports indicated that three members were present, but Francis said he is now being told that as many as 10 were there.
"There is some evidence that might indicate that they were more than observers," Francis said. "It is fuzzy as to what their role was."
Francis said law enforcement officials and civilians have provided first- and second-hand reports on Delta Force activities. He declined to elaborate further.
Evidence gathered after the Mount Carmel fire was in the hands of Texas law enforcement officials until U.S. District Judge Walter Smith Jr. ordered all evidence surrendered to the federal clerk in Waco.
Government attorneys have indicated in some court documents that as many as 10 "classified" military personnel were present, said Houston attorney Mike Caddell, who filed the wrongful death lawsuit on behalf of about 100 people, mostly relatives of dead Branch Davidians.
"We've been told that there were 10 military personnel, but they won't tell us who they were," he said.
Caddell said government attorneys were asked to answer questions in connection with the lawsuit. One of the questions asked for a list of all military personnel who were at Mount Carmel.
Government officials listed Army medical personnel, the Texas National Guard and 10 others whose identity they said is classified information, Caddell said.
Army Col. Bill Darley, a Defense Department spokesman, said the Pentagon has stated that it had only three Special Operations personnel at Mount Carmel and he has seen nothing to refute that statement. Two soldiers were present during most of the siege to maintain high-tech equipment, he said. Another was there when the compound burned, but only as an observer, he said.
"We had a presence there for support only," Darley said. "All other allegations appear to us to be unfounded and without basis in fact."
That distinction is crucial, according to federal law.
If what Barry and Cullen say is true, military personnel may have violated the Posse Comitatus Act, which forbids use of military personnel in civilian law enforcement except in special cases approved by Congress.
The prohibition applies only to direct participation by soldiers in an arrest, search or seizure. Soldiers may train civilian law enforcement agents or provide military vehicles and munitions.
A congressional report determined that all members of the military were present only as observers and that no violation of the act had occurred. The report, "Investigation into the Activities of Federal Law Enforcement Agencies Toward the Branch Davidians," was issued in August 1996 by the House Government Reform and Oversight Committee and the House Judiciary Committee after their 1995 hearings.
Darley said Pentagon policy prevented him from discussing further any of its "special missions units" such as Delta Force.

Drug ruse?

Some evidence suggests that the ATF created a ruse about the possibility of illegal drug manufacturing at Mount Carmel to obtain free military assistance for its Feb. 28, 1993, raid, which left four ATF agents dead and more than 20 wounded.
As early as November 1992, ATF agents were discussing the need for military support with Walker, the agency's Defense Department liaison, according to Treasury Department documents. The ATF is part of the Treasury Department.
But there was a problem.
In a meeting with the ATF on Dec. 4, 1992, Walker informed the agency that it would have to pay the military for the use of its equipment because the military could waive the charges only in anti-drug operations.
At the meeting, Walker jotted a handwritten note that said: "There was no known drug nexus," according to the Treasury Department documents.
The bill would have been considerable. The military assistance at Waco cost about $1 million, according to a General Accounting Office report released Aug. 26. About 90 percent of the cost was incurred by the Texas National Guard and U.S. Army, the report said.
That military personnel can play a greater role assisting civilian law enforcement in drug investigations is a significant exception to the Posse Comitatus Act, passed as part of the 1990 Department of Defense Authorization Act to help fight illegal drug importation.
Before the end of December 1992, the ATF was investigating "suspicion of drug activity" at the Branch Davidian compound, according to the Treasury Department report.
That addition to the points of investigation apparently was based on a Dec. 16, 1992, facsimile from Marc Breault in Australia, who suggested that a methamphetamine lab had once been seen on Branch Davidian premises. Congressional investigators later determined that Breault was a former Branch Davidian who had left the sect on bad terms.
Former Branch Davidians said Koresh had discovered the lab when he arrived at Mount Carmel and had telephoned the McLennan County Sheriff's Department to report it and to ask that deputies confiscate it, but no one ever came, the congressional report said. The building Breault said the lab was in burned down three years before the ATF raid, the report also said.
David Kopel, a former Colorado assistant attorney general and now a researcher for the Independence Institute, a conservative think tank in Colorado, said he was not surprised by the ATF's decision to add "drug activity" component to the investigation.
"All the military wants is the word `drugs,"' Kopel said. "Nobody cares if it's true."
However, the initial application for a warrant to search the compound included nothing about suspected drug violations. After agents failed to serve the warrant on Feb. 28, 1993, the day of the aborted first assault, they applied for another warrant and expanded its scope. That warrant also made no mention of drugs.
The congressional report states that the Feb. 28 raid should have been conducted differently if there was a real concern about the prospect of a clandestine methamphetamine lab on the premises. Because such labs usually contain explosive and toxic chemicals, standard procedure calls for the arrest of lab operators away from their laboratories. Koresh was regularly seen in Waco and could easily have been apprehended, officials have said.
"All those justifying stories have kind of gone up in smoke: drug use, machine guns, child abuse," said Daniel Polsby, a professor at George Mason University's law school who specializes in constitutional law.
The congressional committees eventually determined that the "ATF misled the Defense Department as to the existence of a drug nexus in order to obtain non-reimbursable support."
Darley, the Pentagon spokesman, said he wouldn't comment on any conclusions reached by Congress. But he said the Pentagon concurs with an Aug. 26 General Accounting Office report, which determined that the approval of military counterdrug support was reasonable and authorized.

National Guard involvement

The use of Texas and Alabama National Guard units at Mount Carmel may have violated laws in both states and perhaps the U.S. Constitution.
Convincing state officials that drugs were involved in the Branch Davidian investigation was crucial to involvement of the Texas National Guard.
The Posse Comitatus Act does not prohibit use of state National Guard personnel for local law enforcement, but Texas law does. State law allows the use of its National Guard helicopters for law enforcement only if there is a evidence of drug violations.
On Dec. 11, 1992, ATF Special Agent Jose Viegra met with representatives of Gov. Ann Richards' office to discuss the role of the military in any potential ATF action against the Branch Davidians, Treasury Department documents show.
Viegra was told he could not make use of Operation Alliance, which serves as a clearinghouse for several agencies involved in drug investigations along the Southwest border, unless there was a drug component.
Three days later, according to a Treasury Department memorandum, Operation Alliance officials received a facsimile from the ATF requesting assistance from the Texas Counterdrug Program, which included the National Guard.
Lt. Col. William Pettit, Texas National Guard coordinator of the Texas Counterdrug Task Force, signed off on the request. The ATF fax made no reference to suspected drug violations in the compound, casting Pettit's approval in doubt, according to the congressional report.
After the Feb. 28 raid, ATF Deputy Director Daniel Hartnett wrote Gov. Richards a letter on March 27, 1993, denying allegations that Mount Carmel did not have the necessary drug activity to justify the Texas National Guard's involvement.
"Please let me assure you that nothing could be further from the truth," Hartnett wrote.
Hartnett wrote that 11 sect members "have some prior drug involvement, some with arrests for possession and trafficking." However, when ATF agents were interviewed by Treasury Department officials in a post-siege review, they said that only one Branch Davidian had a drug conviction, the congressional report said.
The use of the Texas National Guard isn't the only questionable Guard involvement.
The ATF also used the Alabama National Guard for aerial photography on Jan. 14, 1993. That task was authorized by a "memorandum of agreement" between the adjutants general of the Texas National Guard and the Alabama National Guard.
According to Texas law, the National Guard from another state cannot be used without approval of the Texas governor. Alabama state law says that its National Guard has no authority to conduct operations outside the state.
National Guard personnel said in a post-raid Guard investigation that Gov. Richards did not approve the use of the Alabama National Guard. Military documents released to Congress during its 1995 hearings indicated that Richards was unaware of the extent of the Texas National Guard's involvement until after the Feb. 28 raid, the congressional report said. Neither Richards nor members of her staff at the time could not be reached to comment last week.
Use of the Alabama National Guard may also have violated the U.S. Constitution, the congressional report said, although that issue was outside the scope of the congressional investigation.
The Constitution specifically prohibits states from entering into treaties without congressional consent. The National Guard Bureau takes the position that use of the National Guard for law enforcement purposes across state lines is therefore strictly prohibited.
"Thus, it appears that the Alabama National Guard entered and conducted military operations in Texas without the proper authority to do so," the congressional report said.
Staff writer Gabrielle Crist contributed to this report.