Christian Longo, 27, was arrested Sunday night in Tulum, Mexico, a resort town 60 miles south of Cancun, said Charles Mathews, the FBI's agent in charge for Oregon.
Longo is accused of killing his wife, MaryJane, 34, and children, Zachary, 4, Sadie Ann, 3, and Madison, 2, then dumping their bodies into two Oregon inlets. He was placed on the FBI's "Ten Most Wanted Fugitives" list on Friday.
A woman who had been in Cancun last month called FBI headquarters after recognizing Longo's photograph, Mathews said. The woman said she met Longo at a hostel and he identified himself as Brad, but later said his name was Mike.
Longo had since been living at a beach camp in Tulum using the name Michael Longo, and was staying in what Mathews called a "grass hut" with another person who didn't know Longo was wanted.
Mathews said Longo had discussed with other campers the possibility of going to Guatemala.
Longo had been asked to leave the hostel after money was reported stolen there, though Mathews said he was not sure if Longo was accused of the theft.
He was arrested without incident by about 20 Mexican law enforcement officers and FBI agents from the American Embassy in Mexico City.
The FBI had said Longo should be considered "armed, extremely dangerous and an escape risk." The television show "America's Most Wanted" had recently broadcast a segment featuring his case.
Longo agreed to be transported back to the United States and did not have to go through extradition from Mexico, Mathews said. Mexico does not normally extradite fugitives who could face a death penalty, since Mexico has no death penalty of its own.
Longo arrived in Houston Monday morning and was scheduled to appear later Monday or Tuesday before a federal magistrate on federal charges of interstate flight to avoid prosecution.
He was being held in a Houston prison and will be turned over to state authorities for extradition to Oregon, Mathews said.
MaryJane Longo's father Jim Baker, of Traverse City, Mich., said police notified family members early Monday that Longo had been caught. He described his reaction as "a sigh of relief."
Baker said the delay in catching Longo had been difficult for his other children.
"I was so busy taking care of things about my daughter that I'd pretty much blocked out thinking about him ... but my kids wanted him caught. They wanted him to pay for what he did to our family," Baker said. "I knew they'd get him eventually. I feel very good about it."
The first hint of what happened came Dec. 19, when a child's body was spotted floating in a coastal inlet near Waldport, Ore. No one claimed the child. Three days later, a little girl was found in the same shallow inlet.
On Christmas Eve, a tip led investigators to Michigan, where family members identified the childreas Zachary and Sadie Ann. Their parents had moved to the Newport, Ore., area from Ypsilanti, Mich., about three months earlier, police said.
Divers found the bodies of MaryJane and Madison two days later in a marina in Newport. Authorities charged Christian Longo with aggravated murder and launched a nationwide manhunt.
Officials say Longo flew to Cancun from San Francisco International Airport on Dec. 27 using a stolen credit card and identification.
A Dodge Durango that Longo allegedly stole from an Oregon car lot was found at the airport, and Longo had been spotted in San Francisco twice in late December.
Longo, who owned a construction cleaning business in Michigan, is named in six lawsuits seeking more than $30,000 and is wanted on two warrants in Michigan for probation violation and a larceny charge. When the Longos moved west last year, they reportedly left behind $60,000 in debts.
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