He was arrested without incident and jailed on a murder charge.
Police had been searching for the 38-year-old biker since last week, when they found Robert Quiroga bleeding to death on a driveway in San Antonio.
Witness Rick Casas subsequently revealed the men had been drinking beer in his backyard into the early hours.
It was a tense evening. Casas said Merla had verbally harassed Quiroga all night long. Fearing a fight, Casas finally asked his friends to leave.
After Quiroga hugged Casas and apologized for the atmopshere, Casas thought they were leaving peacefully - until he heard Quiroga yelling "No, no!" He turned to see Merla attacking Quiroga. He said he didn't realize Quiroga had been stabbed until he saw blood.
"I just saw it on TV right now," said Quiroga's mother of Merla's arrest. "At least he's off the streets and can't hurt anyone."
She said she was holding up reasonably well, but wondered why Merla had been a free man, given his record, which included a manslaughter conviction that resulted in five years probation and no prison time.
"I hope they don't do that this time," she added.
Joe Lopez, the trainer who moulded Quiroga into San Antonio's first world champion and considered him a son, is heartbroken.
The news hardly buoyed his spirits.
"It's good that they caught him," Lopez said. "But it ain't going to bring Robert back."
Merla, known by the nickname "Scarface," grew up just a couple of miles from Quiroga. The two had mutual friends within the Bandidos motorcycle group, who have said the beefy biker had harassed the diminutive boxer in the past.
