The State of Wyoming will ask that a prison sentence be imposed in the case of a man accused of sexually propositioning a young girl.

Carl Ernest Voigt, 57, pleaded guilty Thursday in Natrona County District Court to one count of third-degree sexual abuse of a minor. The charge carries a maximum penalty of 15 years in prison and a $10,000 fine.

In exchange for Voigt's guilty plea, Assistant District Attorney Brett Johnson asked District Court Judge Catherine Wilking to dismiss three other charges against Voigt: one count each of first-degree, second-degree and third-degree sexual abuse of a minor.

Under the plea agreement, Johnson will ask that Voigt be sentenced to no more than five years in prison. It's a case which Johnson called "very frustrating" at Thursday's change-of-plea hearing.

A chief reason for the plea agreement, Johnson told the court, is the complete lack of physical evidence in the case.

Charging papers say the victim used her phone and made a recording of the alleged sexual proposition. The video was either stored on one of the victim's old phones or an SD card in that phone, but investigators were unable to recover either of those items.

However, a number of the victim's family members reportedly saw the video, and made statements to investigators corroborating the allegations against Voigt.

But, Johnson told Wilking, some of those family members started feeling bad for Voigt. Since the initial investigation, a number of those witnesses have changed their stories to some degree, Johnson said.

"This case would have come down to the word of a 12-year-old girl against Mr. Voigt," Johnson told Wilking, adding that he elected to not put the victim through the trauma of testifying at trial.

Public defender Kurt Infanger asked Wilking to reduce Voigt's bond from $50,000 cash or surety to $25,000 cash or surety. In light of three charges being dismissed and Voigt looking at a much lesser sentence as a result, Infanger argued that Voigt is not a flight risk.

Infanger also said Voigt's mother has arranged housing for him, and a bail-bonds company would post Voigt's bond and make Voigt wear an ankle monitor.

Johnson opposed Infanger's request, saying that the three charges, despite being dismissed, show a pattern of behavior by Voigt.

Wilking agreed to reduce Voigt's bond, though she said cutting the amount in half was not appropriate. She lowered the bond to $35,000 cash or surety.

Voigt's sentencing hearing will be scheduled at a later date.