BATON ROUGE - The attorneys for a man accused of murdering his pregnant girlfriend slammed the police investigation into the matter in an exclusive interview with WBRZ Tuesday.

"They don't have a case," one attorney told News 2's Brett Buffington.

The two New Orleans-area attorneys are working to defend now-former Assistant Principal Robert Marks who Baton Rouge Police say killed his mistress, Lyntell Washington, and their unborn child.

Marks was arrested more than a week ago, accused of abandoning Lyntell Washington's toddler in a parking lot in Baton Rouge near Washington's blood-soaked car.

According to documents obtained by The Investigative Unit, that 3-year-old told police Marks tried to clean that blood up. Marks' arrest report says the little girl also told investigators her mother was "in the lake".

"Based on their child witness who them to go to a water body, the body was recovered on land," one of the attorneys says. "They've assisted us in discrediting their own child witness."

Lionel "Lon' Burns and Jerry Settle say in-depth details about the case don't add up. According to the affidavit, police say Washington's body was found precisely where the woman's cell phone led investigators.

Settle and Burns argue that line is contradicted by the extensive search in Ramah where investigators came up empty before the body was found about 2 miles away by farmers.

"Any DNA evidence I would challenge has been contaminated," the lawyers say. "The body laid in a field for many, many days because they didn't even take the search seriously."

Marks' lawyers also argue the man with a wife and a successful career had too much going for him to commit murder.

"The fact that crime is committed and all of a sudden this gentleman that has so much to lose is drug into this, it's about sensationalism," the defense claims.

The evidence against Marks includes cell phone records that tracked a phone to Iberville Parish the night Washington went missing. Records also traced that phone to the same parking lot where her daughter was found. Police say they found text messages on Marks' phone between he and Washington that indicated Marks knew she was pregnant with his child.

"There are always motives in every murder case," Burns and Settle counter. "It is again the Baton Rouge Police Department taking a short route, taking the quick, easy way, instead of doing a thorough investigation."

The attorneys insist Marks is not a murderer and claim that on his day in court, he won't be found guilty.

"This is a circumstantial case, and in order for him to be found guilty of a circumstantial case, the state must exclude every single hypothesis of innocence."

News 2 reached out to BRPD Tuesday and were told that "BRPD will not be commenting on this ongoing investigation."

In a separate interview with Nancy Grace Monday, Marks' wife said she still finds it hard to believe her husband could do something like this.

Marks remains locked up in the parish prison where he faces murder, feticide, child desertion and kidnapping charges.