A Pennsylvania man accused of murdering a pregnant woman he believed was carrying his child began trial this week in a case prosecutors describe as an attempt to conceal a “double life.”

The defendant, Isaac Smith, 30, faces charges of criminal homicide and manslaughter of an unborn child in the death of Karli Short, 26, who was five months pregnant when she was killed in September 2021, according to court documents obtained by local ABC affiliate WTAE.

The court process began Tuesday in Pennsylvania.

The victim hoped to become a first-time mother

According to prosecutors, Karli Short lived at her uncle's house on Furnace Alley in McKeesport, a city southeast of Pittsburgh.

The authorities maintain that the woman and Isaac Smith had maintained a romantic relationship, although the accused later stated that the relationship had been occasional and that he already had a new partner.

Court documents indicate that Short believed Smith was the baby's father and had even asked him for financial help. Two days before the crime, he also sent her messages related to a future gender reveal party.

According to testimony cited by the prosecution, the victim's uncle heard the woman talking on the phone the morning of the murder.

“Are you going to come from the front or the back?” he recalled hearing before she went out into the yard and a gunshot was heard.

Prosecutor's Office assures that the accused wanted to hide their relationship

Allegheny County prosecutors maintain that Isaac Smith lured the victim outside the home and murdered her.

Hours after the crime, the defendant voluntarily went to the Allegheny County police headquarters and participated in an interview lasting approximately three hours, stating that he wanted to clear his name.

During interrogation, he acknowledged having had relations with the victim and stated that he was willing to take responsibility if the child turned out to be his.

A detective testified in court that investigators initially found his statements credible.

However, the prosecution maintains that the defendant acted because he feared that the pregnancy would destroy his new romantic relationship.

The defense insists that the accused wanted to support the baby

Prosecutors argued that, at the time of the crime, Isaac Smith believed he could be the baby's father, although DNA testing later revealed that he was not.

The prosecution further noted that the defendant had recently begun a new relationship and that his partner had just met his parents days before the murder.

According to the prosecution, the suspect had a “clear motive” because he did not want his love life to be exposed.

For its part, the defense tries to demonstrate that the accused was willing to financially support the victim and the baby if paternity was confirmed.

The trial could last approximately two weeks.

Karli Short's obituary noted that she was “extremely excited” to become a first-time mother and expected to give birth in February 2022.