DALLAS (CBSDFW.COM) – A surprise guilty plea at the beginning of Wesley Mathews’ capital murder trial on Monday, did not stop the trial.

The Richardson father pleaded guilty to a lesser charge of injury to a child by omission moments before a Dallas County jury started hearing evidence.

The guilty plea was not a plea bargain or deal with prosecutors.

It’s the defendant admitting guilty to one of the charges in his indictment.

Wesley Mathews at his capital murder trial (CBS 11)

It’s unclear if prosecutors were aware of Wesley Mathews plans to plead guilty to the felony charge of injury to a child, but the trial moved forward immediately afterwards.

Mathews’ attorney told jurors during opening statements that the defendant will admit to lies and mistakes he made during the time his daughter Sherin went missing and was found dead 2 weeks later.

Sherin Mathews (credit: Richardson Police Department)

Prosecutor told the jury not to buy the father’s story that the little girl accidentally choked to death while being forced to drink milk.

They say the little girl with special needs had multiple previous unexplained bone fractures.

Prosecutors began presenting physical therapists who described the progress the child was making in speaking and eating.

Nickie Daraphone was asked about whether it’s possible Sherin was prone to choking.

Prosecutor: “Did she ever choke during any of those our sessions?”

Daraphone: “I never saw her choking on anything. I do recall occasionally when she did not bite something she might have gagged on it a little bit.”

Prosecutors still plan to prove that Mathews killed her daughter and dumped her in a culvert.

But they admit they will not be able to show the jury how Sherin died because her body was so decomposed by the time it was found.

One of the first witnesses Monday was the K-9 searcher who tearfully testified that it was her dog Stella who made the discovery.

“She was down in the culvert her nose pinpoint straight and that was her official indication she was found human remains,” said Stella’s handler Christina Drury.

Mathews’ attorneys admit that the defendant made poor decisions but insist he did not murder his daughter who had special needs.

The judge plans to sequester the jury for what she says will be a three to four-day trial.

Mathews could get anywhere from probation to life in prison.