DENVER (CBS4)– Newly-filed court documents show federal agents electronically eavesdropped and surreptitiously took pictures of murder suspect Harold Henthorn of Highlands Ranch.

A federal magistrate ordered Henthorn held without bond Wednesday. He has entered a plea of not guilty to a murder charge in relation to the 2012 death of his second wife, Dr. Toni Henthorn.

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In newly filed federal court documents reviewed by CBS4, prosecutors acknowledge there has been “electronic surveillance of the defendant and his premises” and “photographic surveillance.”

Henthorn’s neighbors previously told CBS4 that Henthorn apparently suspected he was being watched and listened to during the two-year federal investigation as he was frequently seen using payphones at a grocery store near his home.

Prosecutors say they will turn over to Henthorn’s defense attorney their surveillance records and information as part of the court discovery process. The government says it will turn discovery materials over to Henthorn’s attorney by November 17.

Henthorn was arrested one week ago after a federal grand jury indicted him on a single first degree murder charge for the September 29, 2012 death of his second wife.

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Toni Henthorn fell to her death in Rocky Mountain National Park with Harold Henthorn the only witness. He told investigators his wife was taking a picture during an anniversary hike when she fell. Toni Henthorn was insured for $4.5 million dollars but none of that money has been paid out.

Prosecutors say they also believe Henthorn was responsible for the death of his first wife, Sandra Lynn Henthorn in 1995. In that case, Harold Henthorn was the only witness when their Jeep fell on his wife during a tire change. She died the next day. Henthorn collected nearly half a million dollars in life insurance from her death.

While federal prosecutors now say they believe the first wife’s death was intentional, Douglas County Sheriff’s investigators ruled it an accident in 1995 and closed their investigation after one week. They have now reopened the case.

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