Opening statements began today in the sexual assault case against Lucas Coe.

Coe, 28, is accused of raping 4-year-old Emma Thompson before she died of unexplained injuries including a fractured skull, severed pancreas and tear to the vagina, on June 27, 2009.

The prosecution argued bruises all over Emma's body are signs she was being abused. And Harris County Assistant District Attorney Tina Ansari said Emma, her mother and Coe all had Genital Herpes.

"A little four year old child has a sexually transmitted disease in her genital area. That's very abnormal you will here, very unlikely," argued Ansari.

"Herpes, although it's commonly transmitted sexually, that is not always necessarily the case," said Defense Attorney William Van Buren during his opening statements.

Emma's mother, Abigail Young, is currently serving a 20 year sentence for failing to protect her child. Young had left Emma's father to be with Coe.

Van Buren pointed to an examination by Texas Children's Hospital on June 18 that, he says, found no evidence Emma was being abused. The examination came on the heels of Emma's pediatrician contacting Child Protective Services. According to the prosecution, Emma's doctor believed she was in danger.

If convicted, Coe could face 25 years to life in prison without the possibility of parole.

After opening statements, the prosecution began calling witnesses. The defense expects to have its turn either Friday or early next week.