Nearly five years after 15-year-old Sierra LaMar disappeared from her north Morgan Hill home—never to be seen again—her suspected murderer’s trial began this week. As the defense and prosecution presented opening statements, attorneys on both sides wildly contradicted each other in framing the case’s fundamental aspects

In remarks to the jury Monday, Santa Clara County Deputy District Attorney David Boyd described the “traces” of Sierra—including her DNA—that tie her disappearance and death to defendant Antolin Garcia Torres, 25, of Morgan Hill. Garcia Torres is accused of kidnapping and killing Sierra March 16, 2012, the last day the 15-year-old student was seen alive. Her remains have not been found.

Garcia Torres’ attorney, Al Lopez, spent most of his opening statement Tuesday ripping into the state forensics investigators’ handling of that evidence, saying it may have exposed the samples to contamination. Lopez argued that investigators followed questionable procedures when they concluded that Garcia Torres’ DNA was found on Sierra’s belongings. Lopez further suggested Sierra might still be alive.

“Sierra LaMar is dead, and this man killed her,” said Boyd, pointing at Garcia Torres during his opening statement inside a crowded courtroom at the Hall of Justice in San Jose. The prosecutor then showed the jury—made up of six women, six men and seven alternates—the last known photo of Sierra, a selfie she took on her MacBook Pro computer just after 7am March 16, 2012, the day she disappeared.

Boyd described Sierra’s habits as a “normal teenage girl” who was active on social media and always had her smartphone with her, constantly updating her status and communicating with friends and family. He showed the jury a timeline of known whereabouts for the teen and Garcia Torres around the time of her disappearance, as well as some of the “thousands of pages” of evidence that showed the two crossed paths “for the first and last time” in the hours after Sierra, a sophomore at Sobrato High School, was last seen.

Lopez, on the other hand, told the jury, “You are not going to hear any evidence that (Sierra) was killed, absolutely none.”

He noted that her cell phone continued to send out a signal after she was reported missing by her mother. Boyd previously said moisture from the March 16 rains had intruded the phone, which could have caused the device to turn on and off by itself.

Lopez attempted to pick apart various other arguments Boyd presented. The defense implored the jury to “keep an open mind throughout this whole process. You haven’t heard the evidence yet.”

Garcia Torres is also accused of three unrelated kidnapping attempts in 2009, in which three women were attacked in the parking lots of two Safeway stores in Morgan Hill.

Sierra’s remains have not been found, but Boyd told the jury it is highly unlikely she ran away from home. Not only is it unusual for all of the teen’s social media accounts to suddenly “go dark,” but Sierra was “totally dependent” on her parents as she had no financial means of her own, or even a form of identification other than a school ID.

“Sierra’s body has not been found. The only thing found are traces of her, found in (the) car owned by that man,” Boyd told the jury, again pointing at Garcia Torres. These traces include DNA that matches Sierra’s profile and a hair that was stuck to a piece of rope in the trunk of Garcia Torres’ red Volkswagen Jetta.

Boyd presented photos on a large flat-screen monitor throughout his opening presentation, as he described Sierra’s cell phone and a bag containing her clothes and other belongings. Police found these items in two different locations off the side of the road in the rural areas surrounding her home near the intersection of Palm and Dougherty avenues in north Morgan Hill. Police found her cell phone March 17, 2012, in a field with no tire tracks or footprints around it, suggesting someone had thrown it to the location, Boyd said.

Sierra’s bag, found a couple days later near Laguna Avenue, contained the clothing she wore when she left home that morning to take her routine walk to her school bus stop, Boyd said. This includes the San Jose Sharks sweatshirt she was wearing in her last selfie, underwear, bra and jeans. “That leaves her naked,” Boyd said.

Analysis of other DNA profiles found on Sierra’s jeans show a strong likelihood of a match with Garcia Torres, Boyd told the jury.

Lopez countered that there are “big problems” with the state’s DNA evidence, as well as the analysis that sheriff’s detectives and county crime lab experts conducted. This evidence is a lynchpin of the DA’s case.

Lopez said the prosecutor’s case relies on “background DNA” found on Sierra’s discarded belongings and in Garcia Torres’ Volkswagen. This DNA was found in such small amounts that it could have been transferred to the incriminating locations by a third or fourth party, the defense argued.

Anyone can leave their DNA in a location simply with the touch of a hand, Lopez told the jury, and that material can stay there for years. “This case is not the ‘gold standard’ DNA,” Lopez said. “It’s called ‘contact DNA.’ … It’s too sensitive. You’re picking up everybody’s DNA who touched it. … And you get mixtures from many people in that sample. There is no way of knowing how many people touched it.”

Lopez added that investigators did not follow “DNA protocol” when processing the items from Sierra’s bag. He showed photos of the items placed on a “dirty” cork board before detectives sent them to the contamination-controlled crime lab.

“The government has big problems in this case with transfer” of DNA and potential evidence contamination, Lopez said.

The defense also noted that in the state’s two separate analyses of the genetic material found on Sierra’s jeans, the more recent one excluded Garcia Torres as a possible match.

Plus, photos of the rope do not show any hair on it, despite Boyd’s claim that police found more than 50 such fibers on the item. “The rope was in evidence for four months before they found that hair,” Lopez said.

And while Boyd said Garcia Torres purchased a gallon of bleach and a turkey baster days before Sierra’s disappearance in order to destroy DNA evidence—eliciting gasps from some of the court gallery Monday—Lopez said the defendant’s intent with these items was easily explained. The bleach, Lopez said, was for laundry. The turkey baster was to be used to extract THC from marijuana in order to create a more potent oil or wax—a process he demonstrated to the jury with props. Lopez said an expert witness will testify about this later in the trial.

The defense attorney also refuted the prosecutor’s claims of Garcia Torres’ involvement in the 2009 Safeway incidents.

Lopez told the jury none of the state’s evidence proves Garcia Torres was involved in those crimes, which he said appeared to be standard robberies rather than attempted kidnappings.

Sierra vanished as she walked from her north Morgan Hill home to her school bus stop near the intersection of Palm and Dougherty avenues.

Boyd told the jury that Garcia Torres “learned” from the foiled Safeway attacks to pick a younger, smaller victim, “immersed in her own life, with her headphones in her ears as she walks toward her bus.”

The trial for Garcia Torres is expected to last up to five months. If convicted, he faces the death penalty or life in prison without the possibility of parole.