An Oklahoma rehabilitation center with a controversial regimen — and ties to Scientology — is at the center of an investigation after three young patients died there within the last nine months.

Deaths at the non-profit, non-medical Narconon Arrowhead,  which was founded by Scientology creator L. Ron Hubbard, include 20-year-old Stacy Murphy, 21-year-old Hillary Holton, and 32-year-old Gabriel Graves.

The deaths have spurred an investigation by the state district attorney, as well as a TV expose on NBC's Rock Center with Brian Williams.

Insiders claim the premature passings could be linked to unorthodox methods the center employs, including patients spending up to five hours a time in a sauna for a month straight, and taking large doses of Niacin, a vitamin.

The center — which is licensed though the Scientology subsidiary ABLE (the Association for Better Living and Education) — is "the authority on getting people off drugs," the movement's most prominent celeb, Tom Cruise, said. reported that fellow A-list Scientologist John Travolta said that "compared with other rehabs, [Narconon is] the best."

Asked about the deaths, Narconon Arrowhead CEO Gary Smith said in a statement: "We will continue to cooperate openly with any local and state agencies that are looking into these matters. Our prayers are with the families of the deceased."