An electrician who worked at the federal detention center is scheduled to plead guilty today to having sex with an inmate — an incident made more troubling because the victim should not have been in prison.

Markell Milsap was to plead guilty to a sex abuse charge for a crime that occurred in September 2007 with a female inmate in a storage closet.

The woman was in custody because a urine test came up positive for cocaine use — a result that the woman vehemently challenged as flawed.

It was on the basis of the test that U.S. District Judge Helen Gillmor revoked the woman's supervisory release, similar to probation, for a bank robbery and sent her to prison.

“;Then these horrible events took place,”; said Matthew Winter, the woman's federal assistant public defender.

The 9th U.S. Circuit Court of Appeals later reversed the judge's ruling and ordered the inmate's “;immediate release,”; but by then the abuse had already occurred.

The criminal charge of a prison worker having sex with an inmate is believed to be the first for the 7-year-old high-rise detention facility near Honolulu Airport.

Milsap, 36, of Mililani was to appear in federal court today for the first time on the federal charge, filed Oct. 1 after negotiations between his lawyer, Birney Bervar, and federal prosecutors.

The charge carries a prison term of up to 15 years, but Milsap will likely face a much lighter sentence in the range of a year under federal advisory sentencing guidelines.

Bervar said his client admits having sex with the inmate, but not forcing her as the woman contends. Federal law prohibits guards and other prison workers from engaging in sex with inmates. Milsap's charge is sexually abusing “;a person in official detention.”;

Bervar said a rape charge involving force would carry a much harsher sentence.

Assistant U.S. Attorney Loretta Sheehan said they agreed to the charge after consulting with the inmate. Sheehan said the issue of force can be addressed at Milsap's sentencing.

“;We thought it was the most appropriate charge,”; Sheehan said.

The inmate had served a prison term for bank robbery, then was placed on federal supervisory release, which is similar to probation.

Gillmor revoked the release last year after the inmate's urine sample tested positive for cocaine. The woman protested that she was clean, and twice asked for a chance to take another test that day but was refused, according to the appeals court ruling.

A lab in Virginia confirmed that the sample tested positive for cocaine, but reported the sample had been diluted. The inmate had been observed giving the sample and the worker who administered the test said the inmate did not dilute it.

But her lawyer argued the inmate was not the one who diluted the sample and that the test result should be rejected by the judge.

Gillmor turned down that request. Even though the woman did not testify, Gillmor concluded that the inmate could not be believed because she had a history of “;dishonesty,”; the appeals court noted.

“;Her credibility is in the minus figures,”; Gillmor is quoted by the appeals court. “;If she told me it was daylight, I would go open the window and check.”;

The appeals court said the judge relied on the inmate's past history rather than the evidence presented at the hearing.

Because the defense did not have a chance to question the mainland lab technician, the urine test — the basis for the revocation — should not have been admitted in the case, the appeals court said.

The appeals court also said the inmate's request to give more urine samples undermined the judge's revocation based on the positive cocaine test.

“;We think it unlikely a guilty party would seek out scientific confirmation of her guilt,”; the court said.

It agreed with the defense, set aside the revocation ruling and ordered the inmate's “;immediate release.”;

“;She served all this time when she herself was the one begging to be tested,”; Winter said.

Winter said it is still not known why the sample was diluted.