Girlfriend of Fotis Dulos, allegedly involved in missing mom's disappearance, turns herself in to police

The girlfriend of Jennifer Dulos' estranged husband turned herself in to police Thursday afternoon in connection with the Connecticut mom's disappearance.

Michelle Troconis surrendered to state police in Bridgeport, Connecticut, a day after her boyfriend, Fotis Dulos, was arrested and charged with a second count of tampering with evidence in a case linked to his estranged wife's disappearance.

Jennifer Dulos vanished May 24 while in the midst of a divorce and custody battle with Fotis Dulos. Troconis admitted to state troopers in August that her first two interviews with them were untruthful and she was ready to be fully truthful, police said.

Authorities found written timelines at Fotis Dulos' office they referred to as "Alibi Scripts," allegedly intended for the two to keep their stories straight, according to Wednesday's arrest warrant.

Her statements moving forward provided evidence that resulted in the additional charges of evidence tampering against both she and Fotis Dulos, police said. She was released on $100,000 bond shortly after turning herself in and is scheduled to return to court on Sept. 18. Fotis Dulos will make a court appearance six days earlier.

Fotis Dulos and Troconis previously were charged with tampering with or fabricating physical evidence and hindering prosecution. Both pleaded not guilty.

Norm Pattis, an attorney for Fotis Dulos, confirmed Troconis' arrest in a statement to ABC News.

"Our hearts go out to Ms. Troconis. We are confident that she will, in the end, tell the truth at trial," Pattis said in a statement. "The state is a terrifying enemy, but a clean conscience is a powerful ally."

Investigators believe Jennifer Dulos, 50, suffered a "serious physical assault" in the garage of her New Canaan home, where bloodstains were found, according to arrest warrants. The arrest warrant issued for her estranged husband Wednesday alleged Fotis Dulos asked to have the seats removed from his car, but the auto repair man spoke to police, who tested them and found his wife's blood.

Police previously detailed Fotis Dulos driving to multiple locations, with Troconis, to dump trash bags containing bloody clothes.

The arrest warrant also details in excruciating detail all of the movements of Fotis Dulos on the day his wife went missing, including using neighborhood surveillance cameras and even a camera placed in a school bus.

The Dulos' five children are in the custody of Jennifer Dulos' mother.

ABC News' Aaron Katersky and Emily Sharpiro contributed to this report.