SAN JOSE -- Two years after 15-year-old Sierra LaMar disappeared on her way to her school bus stop, District Attorney Jeff Rosen announced Monday he is seeking the death penalty against the man charged with kidnapping and killing her.

Despite ongoing volunteer searches through the creeks and fields of Morgan Hill, her body has never been found -- a fact that experts say could make a death penalty verdict difficult to obtain. At the same time, some are hoping that the specter of execution could persuade the 22-year-old suspect -- handyman and one-time grocery store clerk Antolin Garcia-Torres -- to finally lead investigators to her body.

This will be the first death-penalty case since Rosen took office in 2011.

"Given the facts of this case and after a comprehensive review by a committee of senior prosecutors, I have concluded that this defendant should face the ultimate penalty," Rosen said in a brief statement Monday.

Garcia-Torres' alleged history of attacking other women contributed to Rosen's decision, he said. After Garcia-Torres was charged in Sierra's disappearance, he was charged with attempting to kidnap and carjack three other women in separate instances four years earlier, when he worked at the Morgan Hill Safeway and allegedly preyed on the women in the parking lot.

After being indicted by a grand jury in February, Garcia-Torres pleaded not guilty to all the charges, including kidnapping and murdering Sierra. The Alternate Defender's Office, which is representing him, expressed disappointment in Rosen's decision, saying it is a missing person case, not a homicide. The case "does not appear to meet any objective criteria for seeking death nor do they appear to match in any manner the facts and circumstances of other cases in this county where the district attorney has sought death," the office said in a statement.

The LaMar family, however, supports Rosen's decision, Sierra's father, Steve LaMar, and cousin, Keith LaMar, said Monday.

"We're glad the DA has chosen to do the right thing," Keith LaMar said. "I don't personally feel society would be safe with someone like that back in it. "

Several members of the LaMar family either met with one of Rosen's deputies or joined a conference call about two or three weeks ago to discuss the death penalty possibility. All but one cousin, who was torn, supported the decision, he said.

Keith LaMar also said Rosen made it clear that pursuing the death penalty is not intended to be a bargaining chip to persuade Garcia-Torres to lead authorities to her body.

"Someone in the family asked, 'Would the DA use that -- is that one of the factors?' " Keith LaMar said. "Rosen responded, 'Absolutely not.'"

But Marc Klaas, founder of the KlaasKids Foundation, who has helped extensively with the ongoing search effort for Sierra, said Rosen's decision could put needed pressure on Garcia-Torres.

"It's obviously going to be a long, hard slog trying to get a jury to recommend execution when you don't have a body,'' said Klaas, whose own daughter, Polly, was kidnapped and killed in Petaluma in 1993. "But perhaps this individual understands now how serious the DA is and would be willing to make a deal to bring Sierra home."

Obtaining the death penalty without a victim's body is rare but not without precedent in Santa Clara County: Mark Christopher Crew is on death row for killing wife Nancy Jo Crew in 1982, where Crew and an accomplice chopped off his wife's head and stuffed her body into a 55-gallon drum filled with cement, but the remains were never found.

Sierra vanished March 16, 2012, as she was walking to the bus stop near her home in an unincorporated and rural farming area just north of Morgan Hill. Garcia-Torres' DNA was found on articles of Sierra's clothing found two days after she disappeared, folded in her Juicy-brand bag and tossed into a field near her home. Sierra's DNA was also found in the suspect's red Volkswagen Jetta.

Rosen's decision to pursue the death penalty against Garcia-Torres comes after declining to do so in six previous eligible cases.

But the lack of a body will present significant challenges, said Steven Clark, a criminal-defense attorney and former Santa Clara County prosecutor.

"There's a certain level of depravity that goes with a successful death-penalty case, where you can detail what the victim went through," Clark said. "The jurors are appalled by and decide that person should no longer be in society."

Even now, between 20 and 30 volunteer searchers continue to scour creeks, woods and fields throughout the South County every Saturday, looking for Sierra.

"As a family member who's lost someone, it's hard to describe," Steve LaMar said. "Holding out that hope is just something that you do."

Staff writer Mark Gomez contributed to this report. Contact Robert Salonga at rsalonga@mercurynews.com. Contact Julia Prodis Sulek at jsulek@mercurynews.com.