Roger Garcia, like so many 19-year-olds, made constant use of cellphone shorthand.

Typing “idk” meant “I don’t know.”

“Wya” was “where you at?”

And “bet” was short for “you bet” or “I agree.”

But it was a uniquely shortened phrase — Garcia’s “all right” — that became central evidence in his double-murder trial in suburban Maryland. As prosecutors stressed to jurors, the term showed it was Garcia who wrote the social media messages that lured two teens into a Montgomery County neighborhood for what became a deadly ambush.

“ ‘Ight,’ ” they told jurors, “says so much.”

One day of deliberations later, the Montgomery jury convicted Garcia of murder and handgun counts in a case Circuit Judge David Boynton has labeled the “massacre” of two teenagers on the eve of their high school graduation in 2017. Garcia, now 22, is set to be sentenced Friday and faces up to 100 years in prison.

The victims, Shadi Najjar, 17, and Artem Ziberov, 18, were enticed to a darkened cul-de-sac in Montgomery Village under the impression they’d be meeting Garcia to sell him an extra ticket to their graduation ceremony, according to trial testimony. Instead, as the boys sat in a Honda Civic, several gunman exited a different car and pumped at least 30 rounds at them. Najjar and Ziberov were killed in the front seat, found still in their seat belts and next to a bloody ticket they had hoped to sell for $20.

Prosecutors argued there were four shooters, including Garcia. The defense said there were only three shooters and Garcia was not one of them.

In earlier trials in the case, shooters Jose Canales-Yanez, Rony Galicia and Edgar Garcia-Gaona were convicted on all charges, including two counts each of first-degree murder. Each of the three — now 28, 27 and 26, respectively — was sentenced to two consecutive life terms in prison.

Garcia was convicted of two counts of a lesser, unpremeditated form of homicide — second-degree murder — as well as two gun counts. He was acquitted of conspiracy- and robbery-related charges.

“Justice was served,” Adi Najjar, the father of Shadi Najjar, said after the verdict was announced in December. “But what parents go through after losing their child will never change.”

In June 2017, even with his graduation ceremony pending, Najjar had already taken classes at Montgomery College. Ziberov, an Eagle Scout, had been accepted to the University of Maryland. His mother, the first witness called at Garcia’s trial, told jurors about the last time she’d seen her son alive — several hours before he was killed.

“We had a nice dinner, full of talk about future plans,” Julia Tewelow said. “We were all full of emotions. . . . I said, ‘Don’t be too late because tomorrow is an important day.’ He said, ‘Okay.’ ”

According to evidence at the trials, a critical event involving Najjar that occurred six months earlier motivated the shooting. Najjar had arranged to purchase marijuana from Canales-Yanez’s wife, according to prosecutors. When he arrived in his car, prosecutors said, he snatched the marijuana without paying and drove over the woman’s foot as he fled. She was not seriously injured, but the incident enraged Canales-Yanez. He wanted to retaliate, according to court proceedings, and took his time doing so.

Canales-Yanez decided to have Garcia make contact with Najjar over the social media platform Snapchat, according to John Sharifi, Garcia’s attorney.

“Jose decided that he would get his revenge. So what does he do? He turns to Roger. He uses Roger,” the attorney told jurors in opening statements. “Jose wants to keep his eye on Shadi and see if he has any opportunity to get even.”

Garcia connected with Najjar over Snapchat on May 31, 2017. It seemed natural. The two didn’t know each other but had gone to the same high school.

The night of June 5, Garcia, Garcia-Gaona and Galicia were hanging out in a trailer where Garcia lived. Garcia looked at his phone and saw that Najjar was on Snapchat looking to sell an extra graduation ticket. Garcia told the others.

Garcia was the youngest and, according to Sharifi, the most malleable of the four. It was the others — all older — who seized the moment to exact revenge, Sharifi said.

One of them, Galicia, grabbed Garcia’s phone, pretended to be him and began communicating with Najjar, according to Sharifi.

“Still got it?” came the first message to Najjar that night from Garcia’s Snapchat at 8:16 p.m.

“Yeah,” Najjar wrote three minutes later.

Canales-Yanez was summoned to the trailer.

Prosecutors presented evidence they said tied Garcia directly to what happened next. It was Garcia, according to text messages, who contacted Canales-Yanez. And it was his style of shorthand, prosecutors said, that proved he was the person who communicated with Najjar on Snapchat to set the trap for the purported ticket purchase.

Prosecutors showed jurors printouts comparing Garcia’s shorthand for “got you” with Galicia’s shorthand. Garcia always wrote “gotcha,” while Galicia always wrote “gotchu.” Prosecutors then highlighted one of the Snapchat messages sent to Najjar the night of the murders.

“I gotcha with gas money,” it read.

Another Snapchat message sent to Najjar, at 10:02 p.m., made it seem like the purported ticket buyer was at a cash machine: “Ight bet im at atm by the way.”

“Roger authored those Snapchats,” Assistant State’s Attorney Marybeth Ayres argued to jurors, “because of all the different ways you spell ‘ight’ and all the phones that we have that show how all four of these guys spell ‘ight.’ ”

Najjar was with his friend Ziberov, who also had at least one extra ticket to sell. There was no evidence linking Ziberov to the earlier botched marijuana sale, and the gunmen were surprised to see him, prosecutors said, but they decided they had to get rid of any witnesses.

By 10:25 p.m., Najjar and Ziberov had been idling in Najjar’s Honda for more than 20 minutes outside a random house along Gallery Court, having followed instructions for where to meet.

Five minutes later, the killers pulled up.

In the first trial in the case, Canales-Yanez and his attorney chose to have Boynton render a verdict. Boynton found Canales-Yanez guilty and said evidence showed that all four defendants had fired into the car. That ruling, as a matter of fairness, was not allowed to be introduced at the jury trials for the others.

At Garcia’s trial, his attorney stressed that Garcia didn’t orchestrate the attack and that he stayed at the trailer.

“The verdict is consistent,” he added in a recent interview, “with a finding that Roger was not in on any plan to murder, that he never left the trailer and that he was not a shooter.”

Prosecutors stressed that even if Garcia never left the trailer, he wrote enough luring social media exchanges to be guilty of the murders that followed.

Ayres went further, arguing that cellphone data put Garcia at the scene and that ballistics evidence showed there were four shooters.

“It was an ambush murder,” Ayres said. “It was almost militaristic.”