Updated after the jump with Facebook banter between Martinez and Ocampo's friends and tagging crews.

[Update, 11:30 a.m.: 18-year-old Bryan Ocampo was arrested at 9:15 p.m. yesterday, on suspicion of stabbing Martinez on his way home from school — perhaps after a fight, perhaps over a tagging rivalry. A Weekly commenter says the 12-year-old was about to graduate from seventh grade.]

An unthinkable act of violence in an Anaheim parking lot today left 12-year-old Juan Martinez, known by his friends as “R2D2,” with multiple stab wounds in the 1500 block of East La Palma Avenue.

The Orange County Register reported that “officers found the boy, a student at Sycamore Junior High, on the ground in the parking area of the single-story Olive Wood apartment complex” at about 2:45 p.m. He was declared dead at a hospital soon after. And by this evening, the Los Angeles Times confirmed that a “person of interest” had been detained in relation to the stabbing.

Martinez' friends Tweeted their shock:

law logo2x blaw logo2x bAccording to the Register, the victim's classmates from Sycamore crowded around the crime scene, waiting behind police tape to learn his identity.

Martinez attended Sycamore Junior High in Anaheim.; Credit: Google Maps

Martinez attended Sycamore Junior High in Anaheim.; Credit: Google Maps

“I'm scared to see what happened,” said eighth-grader Jocelyn Rodriguez. “I am really afraid it could be my friend.”

Friends were still in the dark by late afternoon — Tweeting that Martinez was in surgery at UC Irvine. But that hope was eventually resigned.

R.I.P. Juan Martinez. Check back for updates on the identity of his suspected attacker.

Update, 11:30 a.m.: Broadcast reports say that Martinez and Ocampo engaged in some sort of argument/tussle before the 12-year-old was ultimately stabbed to death.

KCAL9 talked to Anthony Bustos, the boy who was walking home with Martinez from school:

“I saw him get stabbed. He ran across the street and I ran after him to help him, and then he passed out. … I got my sweater, and I put it on his chest so he wouldn't bleed to death. And I was just telling him that it's OK.”

Judging by comments from Martinez' friends, they all knew Ocampo, even though he was six years older. Tweets one:

law logo2x bThe Los Angeles Times did some Facebook stalking to hypothesize that the murder stemmed from a tag-crew rivalry. Apparently, Ocampo tried to cover his ass by posting, “Theres a big scene at the end of my street,cops everywhere -__- what the hell happened?”

Then, “in response to another person's comment that Juan was killed because he 'dissed OTR and DTA,' the Ocampo Facebook user responded, “Nah I never heard that…I didn't even know who he was.'”

Via the Times:

[The victim's] 17-year-old brother, Alex Martinez, said Juan hung around with a tagging crew called Sky's the Limit, or STL, and that Ocampo was a member of a rival crew called Downtown Anaheim, or DTA.

Alex said his little brother — the youngest boy out of six siblings — never allowed himself to be pushed around. “He stood up for himself, and he stood up for his friends,” he said.

A Facebook memorial page for Martinez, “RIP Juan (Lil R2),” is almost at 1,300 members this morning. One friend shouts out:

Stabbing suspect Bryan Ocampo, or "Moto"

Stabbing suspect Bryan Ocampo, or “Moto”

Stabbing suspect Bryan Ocampo, or "Moto"; Credit: Facebook

Stabbing suspect Bryan Ocampo, or “Moto”; Credit: Facebook

Update: The OC Weekly digs deeper through the social-media dirt, identifying the boys' affiliations:

The messages reveal the dead boy and adult suspect belonged to rival tagging crews, STL (Skys the Limit) for Martinez and DTA (Death Town Anaheim Krew) for Ocampo.

In a conversation on Ocampo's wall, which appears to have taken place right before he was arrested, the 18-year-old, nicknamed “Moto,” either doesn't know what's going on or is playing dumb. (Since then, some friends have deleted their posts, suddenly aware the police and media were watching their every move.) Via OC Weekly:

Ocampo (4:30 p.m.): Theres a big scene at the end of my street,cops everywhere -__- what the hell happened?

Serafin Juarez Tinajero: I heard some kid got shanked after school at sycamore jr high

Ocampo (6:30 p.m.): Yea dude bunch of cops came and shit

Dick Fitswell: They killed him. Heard he dissed OTR [Matt's note: On the Run, another tagging crew] and DTA. That's what I just found out.

Ocampo: Nah i never heard that…i didnt even know who he was

Serafin Juarez Tinajero: a bunch of people are spreading rumors and its getting out of hand

Ocampo: Hell yea

Danielle Galvan (10:10 p.m.): They mentiond ur name bryan ocampo as the killer! Is tht u motttoo?? Lol

'Mannyy Mookiee Plass: FREE MOTO!!! . . . FUCKK DA PIGSS!!!!

'Mannyy Mookiee Plass (10:13 p.m.): Danielle Galvan it aint funnyy it wasnt him

Danielle Galvan: Oh I know it ain't,its some real shit! But thy really got moto?

'Mannyy Mookiee Plass: yeaa around 6 hes my neighbor isaw wen he took off

Danielle Galvan: Reaaally!? Fucck,whyyd thy tke himtho? If he ddidnt do it?

'Mannyy Mookiee Plass: ithnkk cuhzz hes frm DTAK

Alejandro J. Malta: wtf i was texting him at that time

Later:

Danielle Galvan (10:20 p.m.): Sooo wht does tht mean jst cuz he's frm dta?

'Mannyy Mookiee Plass: yaa da pigs juss pulled him over n arrested him

Originally posted June 13 at 9:40 p.m.

[@simone_electra/swilson@laweekly.com]

Advertising disclosure: We may receive compensation for some of the links in our stories. Thank you for supporting LA Weekly and our advertisers.