RALEIGH, N.C. — A state audit released Thursday said a North Carolina State University professor took Outer Banks trips using public funds but could not provide documents designed to show the travel was work-related.

State Auditor Beth Wood's office said Thursday that Stacy Nelson, an associate professor of forestry and natural resources in N.C. State's College of Natural Resources, spent nearly $3,400 from state grant funds on two trips in July and August 2011. He and his family stayed in July at the Sanderling Inn near Duck at a rate of $588 per night for three nights, according to the investigative report.

"It wasn’t like staying at a Super 8 or a Motel 6," Wood said.

Without documentation supporting a business purpose, grant funds should have not been used to pay for the travel, the audit states.

Nelson won a grant from the state Department of Transportation for N.C. State University to examine whether high-resolution satellite images could be used to monitor underwater vegetation. The DOT must either mitigate damage to vegetated areas when building across waterways, and satellite imagery could make avoiding those areas easier.

Nelson said he went to the coast to validate data from plant and water samples performed a year earlier in Currituck Sound but did not retain paperwork with those results after they were recorded, according to the audit. University policy required records be maintained at least three years, the report said.

"We have high expectations and systems in place to ensure our researchers are conducting research appropriately and also documenting that research and travel appropriately," N.C. State spokesman Brad Bohlander said. "Because we didn’t catch it first doesn’t mean we wouldn’t have. We do have layers and systems in place to make sure we are appropriately spending public monies."

Nelson told WRAL News that he looked for more affordable accommodations at the coast but simply couldn’t find any. He also said that he included that data and documentation in his final report to the DOT.

Bohlander said Nelson has repaid the DOT for the trips, and N.C. State is emphasizing its record-keeping policies for researchers.

The investigation followed a complaint to the auditor's fraud, waste and abuse hotline.