Pam Nelson considered Nicholas Mullenmaster a good customer and a nice guy.

Still, the Starbucks supervisor said she wasn't entirely surprised to find that the St. Paul man was the one who flushed pounds of hardware nails down the toilet, causing a flood that required the store to close for hours.

For one thing, authorities say, employees noticed that he spent more time in the bathroom than your average customer.

According to a criminal complaint filed last week, Mullenmaster, 38, flushed pounds of nails down the toilet at several locations in Eagan, including Subway, Leann Chin and a city transit station. Mullenmaster is charged with first-degree criminal damage to property for orchestrating the dumps, which caused thousands of dollars of damage to sewer lines.

The complaint says that, in early to mid-August, nails were found in the sewer line in the bathroom of an Eagan Subway on three occasions and repairs were required. Just before the third plumbing problem was discovered, a white male in his mid-30s was spotted on a surveillance camera coming out of the restroom.

Police were called on Aug. 30 because the suspect returned. By then, the manager had a photo of the suspect. Mullenmaster, present when police arrived, asked why employees had his picture and denied any involvement.

Cops went to an Eagan transit station on Sept. 3, where they again found nails had been flushed down the toilet. A man matching Mullenmaster's description had been in the bathroom almost six hours that morning, according to surveillance footage, and a piece of mail found by plumbers had Mullenmaster's name on it.

Officers were also dispatched to an Eagan Starbucks on Sept. 26, where Mullenmaster was a regular. After he left, plumbing issues caused a flood and the store closed for three hours.

The next day, police were called to Starbucks but tracked down Mullenmaster at a nearby Leeann Chin, where the manager said he was in the bathroom. Officers "listened by the door and heard metallic sounds hitting porcelain or tiled surface as well as the toilet flushing."

When Mullenmaster emerged, officers asked him about the bags he was carrying. Mullenmaster set them down and officers heard a clinking sound. Mullenmaster told them they could look inside the bags. One bag held a large number of silver three-inch nails and a recent receipt from Home Depot for a pound of nails.

The nails were the same type removed by the plumber at Starbucks. At the time, officers were told the Starbucks bathroom was still closed and a plumber was forced to cut through the walls to try to fix the damage.

A trial date has not yet been set. Mullenmaster has been charged previously with violating a harassment order and disorderly conduct, plus two counts of trespassing.

Erin Adler • 952-746-3283