A Westbrook man has pleaded guilty to federal charges for a string of armed robberies that put small businesses on edge this spring.

Travis Card appears in court for his arraignment on April 17 in Portland. He now faces as much as 20 years in prison and a $250,000 fine for each of 11 robberies or attempted robberies.

Travis Card, 38, was arrested April 13 in the wake of more than a dozen unsolved holdups in southern Maine. At the time, police said they believed Card was responsible for robbing a Westbrook gas station on April 6. But local departments and FBI agents continued to investigate his connection to similar crimes.

On Thursday, Card entered a guilty plea in U.S. District Court for interfering or attempting to interfere with commerce by robbery at 11 businesses from Old Orchard Beach to Cumberland.

“I’m glad he decided to do that and take ownership of it and take responsibility,” said Joe Salisbury, co-owner of the Daily Grind in Westbrook, one of the businesses Card targeted. “It saves a lot of hassle and heartache for all the victims.”

Earlier this year, local police and the FBI were investigating 14 unsolved armed robberies in less than four weeks, including a cluster of four in a little more than 25 hours. In most cases, the suspect was identified as a white man covered in dark clothing and armed with a handgun entering a small business and demanding cash from employees. The majority of the robberies occurred shortly before closing time at businesses where only one or two employees were present.

The unusual rash of robberies alarmed owner of small businesses and their employees. Police increased their patrols and advised people to comply with a robber’s demands rather than try to resist. But some business owners were frustrated and defiant, and one put a loaded gun behind his convenience store counter when a robber hit a nearby shop.

Westbrook police arrested Card on William Clarke Drive on April 13 at 6:30 a.m. on his way to work. He had a family home in Windham but had been staying with his father in Westbrook. A search of the father’s apartment that day turned up a black pellet gun and a pair work boots that matched footprints at one robbery, according to a prosecution document filed with the court.

The investigators used shoes, surveillance footage, DNA samples and other evidence to tie Card to the crimes. The prosecution document states Card robbed eight businesses in March and April: Riverton Gas Station in Portland on March 20; Lil’ Mart Gas Station in Falmouth on March 21; Good Things Variety in Westbrook on March 22; Express Mart in Cumberland on March 22; the Daily Grind in Westbrook on March 24; Subway in Westbrook on March 26; China Eatery in Old Orchard Beach on March 29; and Gulf Mart in Westbrook on April 6.

He left each business with sums of money ranging from $198 to $650, according to court records. The total amount stolen was nearly $3,000.

The prosecution document also states that Card attempted to rob three other businesses: China Taste in Portland on March 25; Aroma Joe’s in South Portland on March 27; Moby Dick Variety in Old Orchard Beach on April 11. In those incidents, Card left with nothing. At China Taste, a language barrier prevented him from communicating his demands. The clerk at Aroma Joe’s locked herself in a bathroom, while an employee at Moby Dick Variety brandished a club.

During the robberies Card brandished what appeared to be a firearm. The prosecution document identified it as a black pellet gun.

The investigation did not connect Card to similar robberies at businesses in Auburn, Topsham and Brunswick.

Card has a history of theft and burglary convictions dating to 2013. He now faces up to 20 years in prison and a $250,000 fine for each robbery or attempt. His sentencing will take place at a later date. He faced the initial charge for the Westbrook robbery in state court, but Assistant U.S. Attorney Michael Conley said that has been or would be dropped.

“This case reflects investigative work at its finest,” Conley wrote in an email. “Federal, state and local law enforcement agencies worked together and around the clock to identify Mr. Card and take him into custody. Overpraising those agents and officers involved would be an impossibility.”

In the months since the robbery at the Daily Grind in Westbrook, Salisbury said he has made changes to the security procedures at the coffee shop. His employees, including his teenage daughter who had faced the robber, are ready to move on.

“We were hoping that would be the outcome,” Salisbury said of Card’s guilty plea. “That way, people didn’t have to go to court, go to trial.”

Westbrook Capt. Steve Goldberg said the department was glad to see a resolution in the case.

“We were pretty confident that we had the right guy all along,” Goldberg said.