HARTFORD, Conn. (AP) -- Toxicology tests on the body of the Newtown school shooter did not turn up any alcohol, illegal drugs or prescription medications, an official close to the investigation said Tuesday.

Adam Lanza, 20, fatally shot 20 first-graders and six educators at Sandy Hook Elementary School on Dec. 14 before killing himself as police arrived. He also killed his mother at their Newtown home before going to the school.

The official said the toxicology tests were completed about five weeks ago and the results were turned over to Danbury State's Attorney Stephen Sedensky III, who is leading the investigation. The official, who was not authorized to publicly disclose the information and spoke on condition of anonymity, also said at least some victims' relatives were notified of the test results.

Toxicology tests check for a wide variety of over-the-counter medicines, prescription medications and illegal drugs. In Lanza's case, a separate test was performed for marijuana, which usually isn't part of toxicological reviews, and came back negative, the official said.

The test results, which were first reported by The Hartford Courant last week, leave many questions unanswered. Search warrants revealed that Lanza lived in a home surrounded by an arsenal of weapons, but authorities haven't revealed whether Lanza had been prescribed medications or whether he was diagnosed with any disorder that could help explain the massacre.

Illegal drugs and prescription medications were not on the lists of items found at Lanza's home, according to the warrants. Authorities said they did find medical, psychiatric and prescription records in the home, but didn't disclose the contents of those documents.

A state investigation report on the killings is expected to be publicly released this summer.