BATON ROUGE, La. -- Police say a school administrator found dead on the edge of a sugar cane field was pregnant with the child of a former co-worker, who has been accused in the killing.

The Advocate reports Baton Rouge Police cited crime lab findings.

Lyntell Washington's decomposed body was found June 14 in a roadside ditch in Iberville Parish, west of Baton Rouge. Robert Jovantie Marks has been arrested on charges first-degree murder, first-degree feticide, child desertion and aggravated kidnapping of a child.

Marks, 39, is an assistant principal at Brookstown Magnet Honors Academy, where Washington, 40, worked as an instructional specialist. East Baton Rouge Parish school system spokeswoman Adonica Pelichet Duggan has said Marks was placed on administrative leave after his arrest.

Marks' lawyer, Lionel "Lon" Burns, denies Marks killed Washington.

"Let us know when they find who Ms. Washington's killer is," he said when asked about the paternity finding.

Burns said that Marks wasn't read his Miranda rights until after the Baton Rouge Police Department tried to have an "off the record" conversation with him. The lawyer says any comments that police attribute to Marks, including that he admitted to having an extramarital affair with Washington, should thus be disregarded.

Baton Rouge Police Cpl. L'Jean Mckneely Jr. has said Marks acknowledged having a relationship with Washington.

Burns said authorities searched Marks' house as recently as Thursday, having seized the accused man's computer, motorcycle, pickup, cellphone and rifle.

Washington's daughter told detectives that "Mr. Robbie" had hurt her mother, a police report said. The child also said she heard a bang, saw her mom "shaking."

"She further stated that Mr. Robbie was trying to clean the blood and that her mother was 'in the lake,"' the report said.

An autopsy showed Washington died from a gunshot wound to her head, according to East Baton Rouge Parish Coroner Beau Clark, who ruled that her death was a homicide.

Marks told investigators he last saw Washington at a Wal-Mart in Baker about 8 or 8:30 p.m. June 8, the report said. However, police said records for cellphones belonging to Marks and Washington showed the phones travelled to Iberville Parish later that night, arriving there about 9:45 p.m. and leaving approximately 15 minutes later before returning to the area in Baton Rouge where Washington's car was found.

The girl was found alone June 9 near her mother's car.

A co-worker told investigators that Washington was pregnant with Marks' child and had threatened to tell Marks' wife about their relationship, according to a police report. The report says Marks knew Washington was five months pregnant.

Investigators recovered screenshots of text messages between Marks and Washington, who asks him in one message if he is "attempting to avoid his responsibilities with 'our unborn daughter,"' the report said.