GOLDEN • The trial of a former Nevada prison inmate accused of the 1984 killing of a suburban Denver woman ended Wednesday in a mistrial after his lawyers requested he be evaluated to determine if he is mentally competent to stand trial.

The judge declared the mistrial a day after opening statements in Alex Ewing’s trial and granted the defense’s request. The motion is sealed so it is not known why they requested the evaluation.

Ewing, 61, was convicted in August of killing three members of a Denver area family in 1984, six days after he is accused of killing Patricia Smith, 50, in Lakewood. He was sentenced in August to three consecutive life sentences for killing Bruce and Debra Bennett and their 7-year-old daughter Melissa in Aurora.

On Tuesday, Chief Deputy District Attorney Katharine Decker told jurors that there were numerous similarities between the killings of the Bennett family and Smith, The Denver Post reported.

In both cases, the killer entered through an open garage and rummaged through purses and all the victims suffered blunt force trauma consistent with a hammer being used, she said. Both Smith and Melissa Bennett were sexually assaulted and Ewing’s semen was found in the same places at both crime scenes, Decker said.

“Semen and similarities,” she said, employing a phrase she’d use multiple times in her opening statement. “That’s what this case comes down to. That’s how we know the defendant sexually assaulted and killed Patricia Smith.”

However, Ewing’s attorney, Katherine Powers Spengler, said that some critical pieces of evidence had been contaminated and compromised since the killing nearly 40 years ago and that the DNA found on certain items of clothing do not match Ewing’s.

“The prosecution leads you to believe this case is simple,” Spengler told jurors. “The prosecution wants you to trust some DNA, ignore other DNA evidence and look no further. It’s anything but simple.”

Ewing was identified as a suspect in 2018 through DNA evidence while in imprisoned in Nevada, where he was convicted of attacking a couple in the Las Vegas suburb of Henderson in 1984 with an ax handle in their bedroom. The results of a DNA sample taken from Ewing were linked with DNA eventually developed from evidence taken from the scenes of the Colorado killings.