According to evidence and testimony at trial, Swain gathered information about women he wanted to rob and then would attack them, forcing them to inhale the anesthetic halothane and hitting them over the head with a wrench or shooting them with a stun gun.
Lance Larison, a prosecutor at Swain's trial, described Swain as "a serial killer in training."
"A girlfriend told us he kept a list in notebooks of names and license plates of girls he would follow," Larison said. "I think he was working up to something."
It's not clear if Swain knew Nixon. She managed a Longview telephone call center where Swain once worked.
One of Swain's trial lawyers, Rick Hagan, said the evidence and vivid testimony from those who say Swain robbed and attacked them hindered the defense's efforts to convince jurors to spare Swain from the death penalty.
Larson said blood evidence in the case was "consistent with a struggle" inside Nixon's home, where she lived alone.
Deborah Hancock told the Longview News-Journal she and her husband were to have dinner with Nixon that Friday night after Christmas 2002. They stopped by Nixon's house with a carry-out package when she didn't arrive to eat with them. When their knocks went unanswered, they left the food at her front door.
"I can't believe it's been 10 years," Hancock said. "She was very outgoing and very direct, fun, lively. She was just one of a kind."
Swain's execution is to be followed by two more next week in Texas.