STAMFORD, Conn. (AP) – Police say an elderly Stamford woman was stabbed to death during a home invasion earlier this month by either a mechanic who had once worked on her car and remembered her as a generous tipper or by his girlfriend.

Stamford police and U.S. marshals on Friday arrested Harry Gonzalez, 38, of New Haven and Jennifer Kos, 34, of Seymour in the parking lot of a Burger King in Shelton.

They were charged with felony murder and are each being held on $2 million bond. They are scheduled to appear Monday in Stamford Superior Court.

Joanne Trautwein, 75, was stabbed in the neck in her home on Oct. 6. Her roommate, Barbara Kos, 73, was home at the time but saw little of the incident. Both women are retired Greenwich teachers. Police said Barbara Kos and Jennifer Kos are not related.

Police said they believe Gonzalez met Trautwein in 2002, when he worked on her car at a gas station in North Stamford. They said Gonzalez remembered Trautwein and Kos as good tippers and likely thought they would have cash on hand.

Gonzalez went to prison for assault and robbery soon after he worked on Trautwein’s car. He was released three months ago.

Police say he and Jennifer Kos went to Trautwein’s home intending to rob her.

She let them in and one of the two stabbed her in the neck, killing her, police said. They did not say why the robbery turned deadly.

Investigators said they linked Gonzalez and Kos to the killings because neighbors reported seeing two people snooping around the day of the murder. They asked strange questions about Trautwein’s car, probably to determine if she still lived at the home, said police Capt. Richard Conklin.

Conklin said the questions revealed that the couple knew a lot about Trautwein’s cars, so police found the Sunoco station she used. It’s closed now, but the owner turned over employee records.

Police focused on Gonzalez, a convicted felon from New Jersey and Connecticut with a long rap sheet. They found the New Haven halfway house he lived in and the car wash where he and Jennifer Kos met and started dating.

Police found Jennifer Kos earlier this week but had been tracking her around Fairfield County in hopes that she would meet up with Gonzalez. That happened Friday at the Burger King, ending a three-week investigation.

North Stamford residents shaken by the killing said they were relieved by the arrest.

“The worst part of this whole situation has been knowing nothing and having this in the news,” said Allison Rowe, who lives across from the house where Trautwein was killed. “I’m so glad they caught those people. Thank the Lord.”