New Mexico Gas Company "conducted an extensive investigation for gas leaks and carbon monoxide" at the property, the Santa Fe County Sheriff's Office said.

James Gill, Chief Medical Examiner, with the Connecticut Office of the Chief Medical Examiner, is not investigating Hackman's death in his professional capacity. But he offered insight into the tragedy to PEOPLE, theorizing that a “companion suicide” — where a couple dies by suicide together — is not likely.