ANAHEIM -- Two registered sex offenders arrested over the weekend on suspicion of killing four Southern California women over a five-month span have known each other since at least 2012, when they both cut their ankle bracelets and boarded a Greyhound bus to Las Vegas together using fake names.

Steven Dean Gordon, 45, and Franc Cano, 27, were arrested by federal agents on May 8, 2012, after a two-week stay at the Circus Circus Hotel & Casino, according to court documents in U.S. District Court in Nevada. Both were wanted fugitives: Gordon traveled using the alias Dexter McCoy, and Cano chose Joseph Madrid.

Gordon and Cano were arrested Saturday in California on suspicion of killing four women beginning in October. They have not yet been formally charged. Police in Anaheim were to hold a news conference Monday to release more details on the investigation.

Police believe there could be more victims, and the department has contacted other places with missing persons cases across the country, said Anaheim Police Department Lt. Bob Dunn.

The investigation started after the naked body of Jarrae Nykkole Estepp, 21, was found March 14 on a conveyor belt used to separate recyclables from trash at an Anaheim facility. Detectives connected the men to her slaying and to the disappearances last fall of three women who frequented a Santa Ana neighborhood known for drug dealing and prostitution.

Cano and Gordon were ordered to register as sex offenders after being convicted in separate cases of lewd and lascivious acts with a child under 14.

Gordon was sentenced to three years in state prison in a 1992 case, according to court records, and Cano was sentenced to three years in 2007.

After fleeing Los Angeles in 2012, the two were re-arrested, and both pleaded guilty to failure to register as a sex offender. They were ordered to provide DNA samples and have their computers monitored by federal agents, according to the federal documents, which were first obtained by the Los Angeles Times.

The men also checked in with Anaheim police every 30 days, as required, and provided updated photos, fingerprints and addresses, Dunn said.

Police have not provided details on what led them to arrest the men for the killings or how they could have committed the crimes while under police supervision.

Because the two were in compliance with their monthly check-ins, local police had no reason to watch them more closely, Dunn said, and they had not received any requests from other agencies to do so, he said.

The string of disappearances in Santa Ana began in October after Kianna Jackson, 20, of Las Vegas, arrived in the city for a court hearing on four misdemeanor charges of prostitution and loitering to commit prostitution. Her mother said she stopped responding to her text messages soon after she arrived in Santa Ana.

Josephine Monique Vargas, 34, was last seen Oct. 24 after leaving a family birthday party to go to the store. The Times said Vargas had a rough past that at times involved drug use and prostitution, but her mother said she had been trying to better her life.

Martha Anaya, 28, asked her boyfriend to pick up their daughter so she could work on Nov. 12 but stopped responding to his messages later that night. Like the other women, police said she had a history of prostitution.

Estepp had become a regular on a strip of Beach Boulevard in Anaheim long known for prostitution in the weeks before she was found dead.

Dunn said it was unclear whether the women were targeted because of their ties to prostitution.

Associated Press writers Anthony McCartney and Daisy Nguyen in Los Angeles contributed to this report.