The attorney for the educator arrested Friday in the killing of a pregnant colleague whose decomposed body was found in a ditch earlier this week said his client had nothing to do with the woman’s disappearance or death.

Baton Rouge police, however, have said an apparent affair between Robert Marks and Lyntell Washington could have soured recently, possibly giving Marks a motive in the slaying.

Marks, 39, was booked Friday on counts of first-degree murder and first-degree feticide in the killing of Washington, a 40-year-old coworker at a Baton Rouge middle school. Washington was seven months pregnant with a child believed fathered by Marks.

Marks, an assistant principal at Brookstown Middle Magnet School, initially was arrested last week in the kidnapping and desertion of Washington’s 3-year-old daughter, who was found wandering alone in a parking lot. The discovery — along with statements the girl later made in interviews with investigators — led police to search for Washington, whose body was located Tuesday in a sugar cane field ditch in Iberville Parish.

Police are still investigating a motive because Marks has not been cooperating in the investigation, telling detectives little more than admitting he knew Washington, said Cpl. L’Jean McKneely, a Baton Rouge Police Department spokesman.

Marks made no comment Friday as police escorted him to the car that took him to East Baton Rouge Parish Prison despite a number of questions from reporters.

“We continue to press him for information and still no answer and still no emotion,” McKneely said. “This is a heinous and senseless crime.”

Lionel Lon Burns, Marks’ attorney, said his client has asserted his right to remain silent and to speak with a lawyer. But the police apparently kept trying to elicit statements from the defendant, revealing in a police report Marks’ alleged admission of an affair with Washington, Burns said.

Asked whether Marks and Washington had an affair, Burns said he is not addressing “any of the sensationalism as alleged by the Baton Rouge Police Department.”

“(Marks’) wife firmly stands behind (him), and she asserts his innocence, as does his entire family,” Burns said.

Police have speculated a motive could be that Marks did not want anyone to know that Washington was pregnant with his child. Investigators believe Washington wanted Marks to accept responsibility for the child, but he wanted to keep it in the dark.

“He didn’t want anyone to know,” McKneely said.

In a text message to Marks, Washington asks if he was trying to avoid his responsibility for “our unborn child,” according to a police affidavit. Police said this shows Marks was aware that Washington was pregnant.

Burns also criticized the Baton Rouge Police Department, saying it was “reckless” for authorities to publish the statements of a young child. Washington’s 3-year-old daughter, who was found on June 9 near her mother’s car in a parking lot, told police “Mr. Robbie” hurt her mother, who was “in the lake” and now “sleeping,” according to a police report.

The car had blood inside, and the search for Washington began soon after.

A woman’s badly decomposed body was found Tuesday in a sugar cane field ditch between Roseland and Ramah, an area police searched to no avail on June 10. Cellphone records show Marks and Washington were in that area about 9:45 p.m. on the night she went missing and 15 minutes later traveled to Newcastle Avenue in Baton Rouge, where the toddler was found roaming, police have said.

Dr. William “Beau” Clark, the East Baton Rouge Parish coroner, said Thursday that dental records confirmed the body is Washington’s. The affidavit also says a sandal found on the body matched a sandal found in the abandoned car.

An autopsy conducted Wednesday showed Washington was shot in the head, but McKneely said police are still not sure where the shooting may have taken place. No gun has been recovered.

Burns, the attorney for Marks, noted the child told police her mother was “in the lake,” but Washington’s body was found in a field.

“Who was present with that child when any statement was made to law enforcement, and where is the memorialization of that statement?” Burns asked, calling on authorities to produce a video of the child’s interview.

Burns said Marks is now being kept for 23 hours a day in solitary confinement.

“The victim’s body was just discovered almost two days ago,” Burns said. “We express our sympathy for her and her child, who is now without her mother.”

Washington, whose friends have described her as a generous, devoted colleague, was an instructional specialist at Brookstown. Marks, assistant principal of the same school, was placed on administrative leave last week after his initial arrest.

“Ms. Washington was a treasured member of our team and will be remembered for the impact she had on the many lives she touched through her work in our district,” Warren Drake, superintendent of East Baton Rouge Parish schools, wrote in a statement released Thursday. “We will continue to offer support to Ms. Washington’s coworkers and students during this difficult time.”

Burns described Washington’s slaying as a “tragedy” that also is affecting students at Brookstown.

“The children are following this case, and the children are also victimized because they lost two leaders in that school,” he said.