With recovery Monday of data tapes containing personal information on 1.5 million people who were treated at University of Utah Hospitals and Clinics over the past 16 years, officials said Wednesday they doubt the information was compromised, but they can't be certain.

During a press conference Wednesday, Salt Lake County Sheriff Jim Winder said his detectives believe three people were involved, although they're investigating whether there might be others.

Shadd Hartman, 37, of Erda, was arrested and booked into the Salt Lake County Jail for investigation of possession of stolen property and unlawful possession of another's ID or documents, both third-degree felonies. He also had two unrelated warrants.

A couple of hours after the press conference, it was announced that a second person, Thomas Howard Anderson, 52, of Salt Lake City, was also arrested and booked into jail for investigation of possession of stolen property and unlawful possession of another's ID or documents.

Police believe Hartman and Anderson were in possession of the tapes for most of the time they were missing, but police do not believe either man originally stole the tapes.

A third suspect was already in custody at an undisclosed facility on unrelated charges when the tapes were recovered.

When interviewed by detectives, Anderson admitted he had the tapes locked in a cabinet in his garage, according to Salt Lake County Jail documents. He also reportedly provided the sheriff's office with the name of another person who also had possessed the tapes.

It was unknown Wednesday if that other person was one of the suspects already identified by the sheriff's office.

The set of eight data tapes contained billing records and, in some cases, Social Security numbers and medical procedure codes. The data are routinely backed up and taken by courier to a secure vault in Little Cottonwood Canyon. But on June 1, instead of taking the gray metal box containing the data directly to the vault, the Perpetual Storage courier left it in his car overnight in a Kearns cul de sac and the box was stolen. The courier was cleared by investigators but lost his job.

Winder described the three suspects as "individuals with substantial criminal histories." He said it was a crime of opportunity, as officials had suspected, but "they knew relatively early on" what they had.

He rated the likelihood the information had been accessed, which would require "a rather sophisticated tape drive system," at two on a scale of 10.

"It's highly unlikely. ... They are definitely not techies. I don't know if they could find their rear end with both hands."