Authorities found a 3.5-inch hunting knife with blood on it. They said they believe it's the murder weapon used to kill and dismember 49-year-old Herbert White to death in a room at the Continental Hotel in downtown Los Angeles.
A maid discovered the remains on Nov. 29, some stuffed inside a backpack and wrapped in a blank.
Officials with the U.S. Marshals Service on Friday said the Garcias appeared to be under the influence of the drugs when they were taken into custody.
"They were asleep when we kicked the door in," said Matt Brown, a supervisor with the U.S. Marshals. "They were coherent but they looked like they were on the downside of a drug binge."
Authorities said the Garcias had been in contact with people in their home state and that helped them track the couple down.
Police also received numerous tips from the public that led them to the Hollywood hide-out. People recognized the couple from news reports, despite a change of hairstyle.
Police interviewed the couple Friday night. Investigators said that while they couldn't reveal if there was a confession, the Garcias seemed upset about what happened.
Investigators say they believe the Garcias planned to rob White, who had befriended them and gave them money.
White's family says he was a giving man willing to help others down on their luck.
The Garcias are expected to be arraigned in court Monday.
The Associated Press contributed to this report.