Frederick, Md. ? Bruce E. Ivins, the late microbiologist suspected in the 2001 anthrax attacks, had attempted to poison people as far back as 2000 and his therapist said she was “scared to death” of him, according to court testimony that emerged Saturday.

Social worker Jean Duley testified at a court hearing in Frederick on July 24 in a successful bid for a protective order from Ivins – who five days later committed suicide – that he “actually attempted to murder several other people.”

Ivins took a fatal dose of acetaminophen, the active drug in Tylenol, as federal authorities monitored his movements and prepared to charge him with the murder of five people who died from anthrax poisoning in the weeks after the Sept. 2001 terror attacks. An audio recording of the court session was obtained by The New York Times and posted on its Web site.

The glimpse of the man at the center of the anthrax probe came as investigators consider how to proceed in their investigation.

Answers to one of the nation’s highest profile unsolved mysteries are in documents that could be released as early as this week – and help explain how the government chased the wrong suspect for years.

Prosecutors were mulling this weekend whether to close the anthrax poisoning investigation, possibly as early as Monday or Tuesday. If that happens, court documents detailing newly developed scientific evidence that recently led the government to Ivins may be unsealed.

Five people died and 17 others were sickened when anthrax-laced letters began showing up at congressional offices, newsrooms and post offices soon after Sept. 11, 2001.

After wrongly investigating Army scientist Steven Hatfill, the FBI more than a year ago began looking at Ivins, who worked at the same military lab. Ivins, a decorated scientist who was working on an anthrax cure, killed himself last Tuesday.

Two U.S. officials said victims and their survivors could be briefed as early as Tuesday on the final piece of the bioterrorism attacks that confounded the government.

The Justice Department attributed the break in the case to “new and sophisticated scientific tools” that cost the FBI about $10 million. Investigators said the science focused, in part, on how the anthrax strains were handled and who had access to it at the time of the mailings.

FBI scientists were able to isolate strains used in the attacks, and determined they were not as common as previously thought. And that led investigators to Ivins.

Had the same process been available years ago, it would have cleared Hatfill much earlier, according to two people familiar with the FBI investigation who spoke on condition of anonymity.