Steven Carlson was convicted of first-degree murder Thursday for stabbing a 14-year-old Foothill High School classmate 44 times in 1984, when he was 16 years old.

After deliberating for a day, a jury found Carlson, 46, guilty of the April 5, 1984 murder of Tina Faelz as she walked home from school.

Faelz, who was stabbed 44 times, was found dead in a ditch adjacent to Interstate 680, east of the high school. Both attended Foothill and Carlson lived near the murder scene.

The freshman girl usually took the bus home from school, but recently started walking home to avoid being teased by other students riding the bus, her mother, Shirley Orosco, said in a August 2008 interview with the Pleasanton Weekly.

The case remained unsolved for more than 25 years, but prosecutor Stacie Pettigrew said a 2011 DNA test showed that a small amount of blood that was found on Faelz's purse was Carlson's.

Carlson, who has a long criminal history, including convictions for committing lewd acts with a child under the age of 14 and assault, was arrested and charged with murdering Faelz in August 2011.

Family and friends of Faelz cried when the verdict was announced. Carlson, dressed in a white shirt, wearing glasses and sporting a short haircut, looked straight ahead and didn't show any emotion.

Faelz's father, Steve Faelz, said Carlson "got the verdict he deserved and the prosecutor did a bang-up job."

He added, "We all feel good and we give our thanks to all the people who were involved in this 30-year process. This brings closure to us."

Faelz said it was frustrating that the case took so long to solve but he said he believes law enforcement officials worked hard on it all along, and they got the break they needed when new technology provided DNA evidence that connected Carlson to the crime.

Officer Batt, the lead detective on the case at its conclusion said, "I'm pleased with the result. I appreciate the efforts of all those involved in the case before me, as well as the work of the district attorney and the jury".

In Pettigrew's closing argument Tuesday, she said that the DNA evidence proves beyond a reasonable doubt that Carlson is the person who killed Faelz.

Carlson's Lawyer, Annie Beles, told jurors that they shouldn't find Carlson guilty because the evidence is "flimsy" and there are many unanswered questions -- which includes when the DNA evidence was collected, how it was collected, whether it was contaminated and whether it was improperly transferred.

She added that there are many innocent reasons to explain why Carlson's DNA ended up on Faelz's purse because they went to the same middle school and high school and "were in the same proximity with one another."

In addition, there was no motive, fingerprints or a weapon that connected him to the murder.

Pettigrew declined to comment on the verdict and Beles, who wasn't present when the verdict was announced, wasn't available for comment.

When Carlson was arrested and charged in August 2011, his case originally was assigned to juvenile court because he was 16 at the time of the crime.

But on Jan. 12, 2012, a judge ruled that he should be prosecuted as an adult because of the degree of criminal sophistication he displayed in the killing, the severity of the crime and previous failed attempts to rehabilitate him.

Carlson faces a term of 26 years to life in state prison when he's sentenced by Alameda County Superior Court Judge C. Don Clay on Jan. 9.

Editor's note: Information from the Bay City News Service was used in this report.