PROSPECT, Conn. — Connecticut State Police have arrested a 19-year-old who they say set a fire, destroying two Prospect businesses in September 2015.

At 5 a.m. on Sept. 15, 2015, police responded to a structure fire on Waterbury Road. The fire damaged two businesses, the Golden Wok Chinese restaurant and MTM Masonry Inc. and Chimney. Following an investigation, officials determined the fire was intentionally set.

When the owner of MTM Masonry went to respond to the fire, police say he said he found a potato in the tail pipe of his van. He brought the potato to investigators on scene, who sent it to the state forensic lab for potential DNA sources.

Last week, police arrested 28-year-old Matthew Garguilo, of Enfield, in connection with the fire, but said there was another arrest expected. On Thursday, police arrested Garguilo’s girlfriend, 19-year-old Willow Martin of Naugatuck on two warrants.

According to the affidavit, police say Martin was close friends with Breonna Constantino, the step-daughter of the owner of MTM Masonry, but the two had a falling out over money. The warrant says that Martin had lent Constantino money for clothes and was never repaid and Martin allegedly decided she wanted to burn down her father’s business.

When police interviewed a former boyfriend of Martin, he told them Martin told him she and Garguilo went to the business with a can of gas, went in through a window, and poured gas all over the inside of the business. He also told police that Martin mentioned doing something with potatoes, but he could not remember exactly what she said. He did tell police that a few days after the fire, Martin was pulled over and questioned by the police about a potato.

Police then interviewed Garguilo who told them Martin hated Constantino for not paying back the $1,200. He told them one night, Martin texted him that she wanted to burn down the business. Garguilo said he brought her because he didn’t want Martin to find another guy to bring her, so he went with her to get the gas then drove to the Waterbury Road business. He said he hid in a bush while Martin poured the gasoline on the business and allegedly lit a napkin to start the fire. Garguilo said he and Martin then left, but drove back to the business a few hours later where they saw the business fully engulfed in flames. When asked about the potato, Garguilo told police that Martin wanted to put the potato in the tail pipe because she heard it could blow up the engine. He said he saw her put the potato in the tail pipe, but said he knew she didn’t put it in far enough to do anything.

Garguilo also told police to talk to the manager at Hollywood Strip Club in Southington where the two girls worked. The manager told police that the two worked there last summer and that Martin still does, but Constantino has not in awhile. The manager said the two began working as best friends, but eventually could not even work together due to a dispute.

Martin, who was already incarcerated in New Jersey on unrelated charges, was arrested on Thursday. She is charged with second-degree arson, conspiracy to commit arson, third-degree burglary, conspiracy to commit burglary, possession of burglar’s tools, conspiracy to commit possession of burglar’s tools, first-degree criminal mischief, and conspiracy to commit criminal mischief.

She is being held on a total of $110,000 bond.