"He committed unspeakable acts of horror upon that beautiful young woman," said Murphy.
Police say Alcala likely spotted beautiful Charlotte Lamb in a local bar and tried to approach her.
"Before Rodney Alcala, just like the others, a beautiful young woman," said Murphy. "After Rodney Alcala she's a brutalized, ripped-up corpse."
Lamb was discovered in the laundry room of her building.
"He posed her dead body," said Murphy. "He propped her arms up under her back, probably to arch her up so that her breasts would be better exposed."
One year later, Alcala was spotted dancing at a bar with an attractive 21-year-old named Jill Parenteau. Just a few days later, Parenteau was found dead, her tortured body posed in almost the exact same fashion as Wixted and Lamb.
"Living alone, another independent person," said Shepard. "That was just another brutal, brutal murder."
Just six days after Parenteau's body was found, Alcala met his youngest victim, 12-year-old Robin Samsoe. The girl was riding her bicycle to her very first ballet class when Alcala allegedly convinced her to get in his car. Her body was found 12 days later.
"Robin was in the innocent child stage of 12," said Murphy. "All she cared about was ballet. ... He turned this beautiful young girl into a rotting corpse, eaten by animals."
Alcala has been twice convicted for the murder of Robin Samsoe, but both times the verdicts were overturned.
"I wish I had a gun again today," the girl's mother, Marianne Connely, told ABC News.
Connely was in court, once again facing her daughter's accused killer. During the first trial, in the days before metal detectors, she says she carried a pistol in her pocketbook when she took the stand, with the intent of making her own justice.
"He was blowing kisses at me across the courtroom, and I thought I was going to lose my mind," Connely said. "And I thought I was going to go crazy, you know. And I reached into my purse and I was going to grab it, you know, and I thought, 'I can't do this.'"
Police say Alcala has spent more than 30 years obsessing about the murder of Robin. He has even written a book proclaiming his innocence.
Robin's brother Tim Samsoe, 44, said the worst thing is watching Alcala perk up in court every time he get the chance to see old photographs of his alleged victims.
"You see the gleam in his eye," said Samsoe. "He's enjoying this again."
Alcala is accused of using his skills as a photographer to lure his victims. Four different women still recall Alcala trying to get them to pose for him in their bikinis on the beach for a "photo contest" on the day Robin disappeared.
More than 1,000 photos taken by Alcala were found in a storage locker in Seattle, including bikini photos shot the day Samsoe disappeared.
"You walk up, camera in hand, polished demeanor," said Hodel. "You say, 'You want to be in pictures?' Basically, he was a skilled photographer."
There may be clues to countless other victims among photographs obtained exclusively by "Nightline."
"We know he's been cross-country a couple of times," said Shepard. "We know we have victims on the East Coast and the West Coast. We believe there's more out there. ... It wouldn't surprise me if we ended up with 10 to 15 more."
In New York City, authorities say there is evidence of at least two other murders committed by Alcala. But he has never been charged in those killings.