The year is 1978, and the syndicated show "The Dating Game" is a household hit from coast to coast. A bachelor on one episode stands out for his looks and charm as he answers questions posed by a bachelorette in search of a date.
"Bachelor No. 1, what's your best time?" she asks.
"The best time is at night, nighttime," says the bachelor, whose name is Rodney Alcala.
"Why do you say that?" she asks.
"Because that's the only time there is."
What's wrong with morning or afternoon?"
"Well, they're OK, but nighttime is when it really gets good. Then you're really ready."
The bachelorette seems intrigued by 35-year-old Alcala. The audience also seems to think he's handsome and charming. In the end, Alcala wins the date.
But what the bachelorette doesn't know is that the man she just picked may turn out to be one of the most brutal and terrifying serial killers in history.
Watch the full story Thursday on "Nightline" at 11:35 p.m. ET.
"This could easily be another Ted Bundy," said Steve Hodel, a retired detective with the Los Angeles Police Department. "It could be 20, 30 victims." Now, 66-year-old Rodney Alcala is charged with murdering four California women and one girl in the late 1970s. Arguments in his multiple murder trial, in which he is representing himself, closed today. The case, at Orange County Criminal Courthouse in Santa Ana, Calif., is now in the hands of the jury.
Some investigators believe the five killings are just the tip of the iceberg.
"He's right up somewhere just below Hitler and right around Ted Bundy," said Det. Cliff Shepard, an LAPD cold case investigator. "There is no rhyme or reason for what he is doing. I mean it is not humane, whatever he does to these victims. It is a torturous, terrible murder."
By many accounts, Alcala was a man with a bright future. He had a Fine Arts degree from the University of California-Los Angeles, studied film at New York University and had worked for director Roman Polanski.
"I talked to his professor at UCLA and his professor came out and said this guy is a top honor student," said Hodel. "He is really a nice guy. He wouldn't hurt a fly. You've got the wrong man. ... I got this very smart, very polished guy and ... the acts he committed, you've got this monster inside of him."
Investigators said the slayings happened between late 1977 and mid-1979.
One of the alleged victims, Jill Barcomb, was a free spirit. In 1977, when she was just 18, she traveled from her home in Oneida, N.Y., out to California with friends. She was in Hollywood for only a few weeks when she met Alcala.
Shepard took ABC News to the site where Barcomb's body was found.
"Jill's found right here," said Shepard, "around Franklin Canyon Drive, Nov. 10, 1977."
It isn't clear how Alcala allegedly picked up Barcomb, but police say the ending is certain.
"What he was doing was choking her out unconscious, bare-handed, and allowing her to regain consciousness because he enjoys that," said prosecutor Matt Murphy at Alcala's trial. "He gets off on the infliction of pain on other people."
Only one month later, prosecutors said, Alcala spotted beautiful 27-year-old Georgia Wixted, who had just recently moved into her first apartment.
"He followed her home. He crawled in her window and he absolutely brutalized her," said Murphy.
Wixted was found dead Dec. 16, 1977.