California serial killer Rodney Alcala pleaded not guilty Thursday after being charged in the killings of two New York women in the 1970s.

Alcala was extradited to New York on Wednesday after cold-case detectives spent a year reviewing the two slayings.

Authorities have long suspected that Alcala, who has been held in a California prison under a death sentence, had struck outside of California. New York authorities have been investigating links between Alcala and the two women for nearly 10 years.

The photographer and onetime "Dating Game" contestant was convicted in 2010 of murdering four Los Angeles County women and a 12-year-old girl from Huntington Beach in the late 1970s. He was sentenced to death.

After his conviction, police detectives released a trove of photographs of women and children they seized more than 30 years ago from a storage locker Alcala rented just as police were closing in on him. Detectives said they wanted to know who these people were and whether they might have gone missing during Alcala's murder spree in the late 1970s.

Manhattan prosecutors charged Alcala several months ago in the deaths of flight attendant Cornelia Crilley and researcher Ellen Hover.

"These cases were built one brick at a time, as each new lead brought us closer to where we are today," Dist. Atty. Cyrus R. Vance Jr. said at the time, according to the Associated Press. He said he hoped that the belated action "brings a small measure of peace to the families and friends who have spent decades searching for answers, and justice."

Seattle police have also investigated him in connection with some unsolved slayings.

This story was reported by Times Staff Writer Shelby Grad.