The 66-year-old is on trial a third time for the murder of Robin Samsoe, a girl from Huntington Beach. Alcala was convicted twice before, and twice those convictions were overturned.
Jurors heard how a man, who was later identified by Samsoe's friend as Alcala, had asked to take their picture at the beach in 1979.
Not long after that, prosecutors allege Samsoe was on her way to ballet class when Alcala abducted her. Her mutilated remains were found two weeks later in the Angeles National Forest.
"Robins' head was separated from the rest of her body, both her hands were missing, her front teeth were cracked," described prosecutor Gina Satriano.
Prosecutors allege that Alcala kept Samsoe's earrings in his storage unit in Seattle where he moved after her murder. Prosecutors say detectives also allegedly discovered earrings belonging to 32-year-old legal secretary, Charlotte Lamb. Her body was found in the laundry room of her El Segundo apartment complex in 1978.
Prosecutors allege that DNA links Alcala to four murders. The women were sexually assaulted, severely beaten and strangled. Many of the injuries were inflicted while the women were still alive.
Eighteen-year-old Jill Barcomb's body was found on a remote road in the Hollywood Hills in 1977. A month later, Georgia Wixted, a 27-year-old nurse, was found dead in her Malibu apartment.
In 1979, just days before Samsoe's abduction, 21-year-old Jill Parenteau was found in her Burbank apartment, beaten and strangled with her nude body posed.
"It's been very devastating for my family," said Dedee Parenteau, the victim's sister. "She was kind and gentle, full and with wonderful sense of humor."
Some family sobbed, some seeing Alcala for the first time in person.
Alcala has pleaded not guilty to all the charges. He deferred his own opening statement until later in the trial.