Missing mom's husband pleads not guilty to new charge; 'Bring it on,' defense says

Fotis Dulos and his girlfriend, Michelle Troconis, are both facing charges.

Fotis Dulos, the estranged husband of missing Connecticut mom Jennifer Dulos, pleaded not guilty Thursday to a new charge that he tampered with evidence in the case.

"Mr. Dulos is not guilty," his attorney, Norm Pattis, told reporters after the court appearance in Norwalk. "We've got three words to the state: Bring it on."

Fotis Dulos was first arrested in June on charges of tampering with or fabricating physical evidence and hindering prosecution in connection with Jennifer Dulos' May disappearance.

Fotis Dulos' girlfriend, Michelle Troconis, was arrested on the same charges. Both pleaded not guilty.

Fotis Dulos and Troconis were then arrested again in September on another charge of tampering with evidence. Fotis Dulos' Thursday court appearance was in connection with the new charge.

According to an arrest warrant, police found handwritten notes Fotis Dulos and Troconis allegedly used to establish a false timeline of events to keep their stories straight, dubbed by detectives as "alibi scripts."

Police also provided several screenshots allegedly showing Fotis Dulos using a car belonging to an employee’s wife the morning of Jennifer Dulos’ disappearance, documents said.

That employee told investigators that Fotis Dulos told him to replace the seats in the car and to dispose of the ones that were in the car the morning Jennifer Dulos disappeared, documents said.

The employee didn't comply with Fotis Dulos' alleged instructions and gave the car seats to investigators, who, after testing, found the missing mom's blood on the seats, documents said.

Jennifer Dulos, who has five children with Fotis Dulos, was last seen on May 24, vanishing amid a contentious custody battle with her estranged husband.

Investigators believe Jennifer Dulos, 50, suffered a "serious physical assault" in the garage at her New Canaan home, where bloodstains were discovered, according to arrest warrants.

Clothes and sponges with Jennifer Dulos' blood were found in trash cans in Hartford, where surveillance cameras captured a man appearing to be Fotis Dulos disposing of garbage bags, according to the documents. A woman in the passenger seat of the man's car fit the appearance of Troconis, according to the documents.

Fotis Dulos returns to court on Oct. 4.

Troconis is due in court on Sept. 18 on the new tampering with evidence charge.

ABC News' Carlos Boettcher contributed to this report.