HAGATNA, Guam >> A jury convicted a Guam man Monday of murdering three Japanese tourists in a crash and stabbing rampage last year that hurt 11 others.

The panel of 10 women and two men rejected the mental illness defense of 22-year-old Chad Ryan DeSoto. His lawyers argued he spiraled out of control into psychosis after his grandfather died and his girlfriend moved to Utah.

The jury agreed with prosecutors who say DeSoto knew what he was doing during the attack in a busy tourist spot on Feb. 12, 2013. DeSoto was accused of barreling his car down a busy sidewalk, crashing it into a convenience store and getting out and stabbing people who were nearby.

DeSoto was also convicted of attempted murder. He faces life in prison without the possibility of parole when he is sentenced Sept. 25.

“Justice has been done for the families of the victims,” Chief Prosecutor Phillip Tydingco said. “I want to thank all the jurors for doing their duty and for the hard work. I know it was long and grueling for them.”

DeSoto, dressed in a white Oxford shirt with a gray sweater-vest and gray slacks, showed no emotion as the verdict was read. Each individual juror verified his or her decision in a hearing that lasted 10 minutes.

“I am just thankful the jurors hung in there and made it through deliberation,” said DeSoto’s lawyer, public defender Jocelyn Roden. “I still have my faith in the justice system.”

Guam’s attorney general planned a news conference for later Monday.

The rampage rocked the small island U.S. territory and raised questions of tourist safety in Japan and elsewhere. Guam’s economy depends heavily on tourism.

The tourists killed were 81-year-old Kazuko Uehara and 29-year-old Rie Sugiyama, who were stabbed to death; and Hitoshi Yokota, 51, who was hit by a car and died in a hospital two days later. Another 11 people were injured, including two children.

Prosecutors argued DeSoto planned the attack, targeting victims who resembled or symbolized his girlfriend, who had recently dumped him.

The jury received voluminous instructions before starting deliberations July 18, with jury instructions that took nearly five hours for Judge Anita Sukola to read and more than 100 pages of verdict sheets. The instructions included information on convicting DeSoto of lesser offenses.

Sukola said that during the Sept. 25 sentencing, she will set a future hearing for accusations that DeSoto, his girlfriend and one of his relatives violated a court order by communicating during the trial.