WACO — The official in charge of a team investigating the April 19 blaze that leveled the Branch Davidian cult compound outside of Waco defended his team’s finding Thursday that the religious zealots had deliberately set the fire.

More than 70 people perished in the burning building, which caught fire as FBI agents assaulted it with tank-like vehicles in an effort to inject tear gas.

Critics, including attorney Dick DeGuerin, who had been representing cult leader Vernon Howell, have suggested that arson team chief Paul Gray may have been too close to the U.S. Bureau of Alcohol, Tobacco and Firearms to conduct an unbiased investigation.

Gray, an assistant chief investigator with the Houston Fire Department, said he determined that the blaze started “in at least two places” and discounted the stories that the FBI started the fire accidentally.

“This investigation is the most meticulous crime scene search in my recollection and possibly in history, except perhaps for the World Trade Center bombing, Gray said.

Critics question the findings, however, and note Gray’s association with the ATF, whose Feb. 28 attempt to serve warrants at the compound began the standoff.

Gray’s wife is a secretary in the Houston ATF office, and he has taught in the ATF’s academy, as many other arson investigators have. From 1982 until 1990 Gray was the Houston Fire Department’s liaison to the ATF.

Gray said he has “never taken one penny from the federal government” despite sharing office space with the ATF in the 1980s.

Gray also discounted any conflicts he might have because of his wife’s employment.

Read the Tribune-Herald's 7-part investigative series on the inner workings of the Branch Davidians. Hours after Part Two appeared in print, the ATF raided the group's compound.

Read the Tribune-Herald’s account of the ATF raid on the Branch Davidian compound on Feb. 28, 1993. Four ATF agents and six in the compound were killed in the gunfight.

Read the daily news accounts of the 51-day siege at the Branch Davidian compound near Elk, which began Feb. 28 and lasted until April.

Read the accounts of April 19 and beyond: FBI agents began inserting canisters of tear gas into the Branch Davidian compound in the early morning hours. By noon, it was on fire.

Federal officials left the compound site in late May 1993. As identifications of bodies continued, questions about the survivors, the compound and the cult itself began to emerge.

As the world began to take a critical look back at the events and legal proceedings continue, the ATF's bombshell report forces a shakeup at the top after the raid gone "tragically wrong."

The 1987 Rodenville shootout and trial, the end of the world in 1959 and more coming soon.