The competency hearing for Christian Martinez went to a jury Wednesday morning and the jury decided he is competent to stand trial.
Martinez, 21, is charged in the deaths of Amalia Flores, 58, and Jovana Flores, 20, in January 2011.
A psychiatrist who first evaluated Martinez testified that he was competent to stand trial, but days later reversed his opinion.
The psychiatrist said Martinez's mental health worsened during the year and a half that he has been behind bars.
Martinez allegedly stabbed Amalia and Jovana Flores to death inside their east El Paso home.
Police say Martinez followed Jovana home after he came across her while she returned from a jog.
After allegedly killing the victims, Martinez is believed to have rummaged through the home, police said. Martinez was found inside the home with a serious laceration to his left wrist that required hospitalization.
Martinez now faces capital murder charges.
The prosecution and defense argued Wednesday over the relevance of Martinez's health evaluation from May of last year.
That evaluation was struck down by the judge because it was out of date.
During closing arguments Thursday morning, the prosecution reiterated to the jury that even after one psychiatrist said Martinez exaggerated some of his responses during a mental evaluation, he still passed.
The defense argued that prosecutors did not bring in a single doctor to evaluate Martinez.
"Just because he is incompetent to stand trial doesn't mean he is going to walk out of this courtroom, said Joe Spencer, Martinez's defense attorney.
"He is in the 2 to 3 percent, where 97 percent of people are more intelligent than him, and it's not his fault," said Spencer.