The assistant chief declined to elaborate on what role drugs may have played in Susan Powell's 2009 disappearance.
Mike Powell emphasized that the Rocky Mountain HIDTA audit found the expense was "reasonable" and "justified" but that it did not meet the grant criteria.
Tom Gorman, director of Rocky Mountain HIDTA, said then-West Valley City Police Chief Thayle "Buzz" Nielsen agreed to return the money when questions were raised.
"It wasn't a big enough [drug trafficking] case that would warrant spending our money," Gorman explained, adding that he could not further explain why the money had to be returned.
Mike Powell said the reimbursement was voluntary.
Susan Powell was last seen Dec. 6, 2009, at her West Valley City home. Her husband, Josh Powell, claimed he left about midnight and went camping in the West Desert with his sons, then ages 4 and 2.
Josh Powell remained a person of interest in the disappearance until Feb. 5, 2012, when he murdered the boys, Charlie and Braden, at his rental home in Graham, Wash., and set the house on fire, killing himself.
Steve Downing, an attorney for Susan Powell's parents, has theorized Josh Powell poisoned or spiked pancakes he cooked for his wife the night she disappeared.
Susan Powell has never been found.
The $17,090 is a portion of what West Valley City receives from Rocky Mountain HIDTA and represents a fraction of what the city has spent on the Susan Powell investigation, which has included utilizing dozens of officers from the West Valley City Police Department and sending them on trips to multiple states.
West Valley City leaders have said they have never calculated the investigation's cost.
It's the first time the Susan Powell disappearance has come up directly during the recent problems at West Valley City. Two West Valley City detectives remain on leave for the November fatal shooting of Danielle Willard, and the Salt Lake County district attorney continues to weigh whether the shooting was justified.
Since the shooting, questions about evidence handling and procedures by West Valley City police have resulted in 125 state and federal cases being dismissed. And prosecutors are reviewing about 400 more.
Mike Powell said detectives continue to investigate aspects of the Susan Powell disappearance.