Covington Police Chief Tim Lentz has launched an investigation of the department’s confidential informant fund after a surprise audit last month raised questions about the fund and two officers who received checks totaling $18,500 from it in 2013, he said.

A notice of investigation sent to Sgt. Stephen Culotta and Detective Bart Ownby said the department is investigating “an incident involving you’’ in a matter discovered in April. It cites three checks paid to Culotta totaling $15,000 and one to Ownby for $3,500.

The checks were drawn on a city account designated for “confidential informant funds,’’ the notice says.

The notice of investigation, which was delivered to the officers Wednesday, assigns them to the Criminal Patrol Division while the investigation is ongoing.

Lentz, who abolished the Covington department’s one-officer Internal Affairs Division shortly after being hired, has asked the Mandeville Police Department to conduct the probe.

Lentz, who became chief late last year, said Friday that in taking the job he promised he would evaluate the department and, if he encountered things that were questionable or warranted further investigation, would “address them head-on.’’

He said he is working to rebuild trust in the department, which was eroded by allegations of excessive force and a dispute between Mayor Mike Cooper and former Chief Richard Palmisano that eventually resulted in Palmisano’s dismissal a year ago.

In outlining the events following the surprise audit last month, Lentz said in the notice of investigation that Culotta had promised to provide a recap of the questioned spending within an hour but that it took him 27 hours to provide what the chief described as a spreadsheet. Lentz then asked for paperwork to back up the spreadsheet, and Culottta provided “a binder full of paperwork justifying the expenditures.’’

But the paperwork raised more questions, Lentz said.

The notice of investigation offers a list of alleged inconsistencies. Some appear to be minor, such as a picture of a gas pump that was submitted as a receipt or missing signatures on informant payment forms.

Some appear to be more substantial, such as a report claiming an informant received payments of $150 and $100 while records reflect only the $150 payment.

Confidential funds also were allegedly used to buy handguns, but no evidence sheet was attached to show the guns were taken into custody or turned into evidence.

Further, police reports make no reference to the use of an informant in cases where informants supposedly were paid, the notice says. In one case, an informant was paid $295 from the fund to stay in a hotel, when a receipt for the same day and same amount shows it was paid in cash by Capt. Jack West, who has since left the department.

The notice also mentions Ownby writing that he gave one informant money to “pay off crack cocaine debt.’’

“The above examples are not all-inclusive,’’ Lentz says in the notice. “There are many questions that warrant investigation.’’

Culotta and Ownby did not respond to requests for comment.

“This investigation is an opportunity to fully explore what happened, and to determine if any department policies were violated,’’ the notice says.

“In many cases, officers are fully exonerated once we have all the facts, but state law requires us to provide you with this notice prior to discussing the situation with you if there is a possibility that disciplinary action could result.’’

Follow Sara Pagones on Twitter at @spagonesadvocat.