PITTSBURGH — Pittsburgh former police chief Nathan Harper is facing sentencing for conspiring to create an unauthorized slush fund from which he spent more than $30,000 on himself.

U.S. District Judge Cathy Bissoon was scheduled to decide Tuesday whether Harper deserves prison, probation or some in-between alternative, such as house arrest.

Harper, 61, resigned last February, a few weeks before he was indicted on conspiracy charges and failing to file tax returns between 2008 and 2011, when much of the money was misappropriated.

Harper pleaded guilty in October to conspiracy to commit theft and the tax charges; his attorneys have since argued his otherwise spotless service record make probation appropriate.

But federal prosecutors contend Harper helped lead the conspiracy by directing underlings to create unauthorized credit union accounts and he deserves between 18 and 24 months in prison.

Harper joined the department in 1977 and rose through the ranks to become chief in 2006 under the recently departed mayor, Luke Ravenstahl.

Ravenstahl abruptly dropped his re-election bid in March — three weeks before Harper was indicted — saying speculation about the investigation and his personal life had become too much of a burden for him and his family.

Ravenstahl and his attorney have repeatedly denied wrongdoing. Authorities have not charged Ravenstahl, though the former mayor has acknowledged his police bodyguards had credit cards linked to the same unauthorized accounts for which Harper was prosecuted.

One of the bodyguards has said the investigation centers on whether city money was misspent by having the guards drive the divorced 34-year-old mayor to and from bars after business hours.

In pleading guilty, Harper acknowledged diverting more than $70,000 in fees the city collected from businesses that hired police officers to work off-duty security details into two unauthorized credit union accounts. Harper then spent nearly $32,000, mostly for his own benefit.

Putting the money into unauthorized accounts is considered theft because funds belonging to an agency that receives federal money — like the Pittsburgh police bureau — must be kept in official government accounts.

Though Harper's attorneys acknowledge he directed two underlings to set up the accounts, they claim Harper was only following orders — though they haven't said from whom. Creating the accounts enabled Harper and the police bureau to spend money that would not be traceable in the same way normally budgeted police funds would have been.

Federal prosecutors haven't charged anyone else in the scheme and have refused to comment on defense claims that Harper was ordered to set up the accounts.