RANCHO CORDOVA -- Police in Rancho Cordova say a letter is being sent to residents claiming to provide details about the East Area Rapist case.
The letter, police say, "is not an authorized document from a law enforcement agency."
The police department added that any updates about the case would be "properly labeled" and sent from official channels.
The anonymous author goes by "Snake Slayer."
Sacramento County Sheriff's Sergeant Shaun Hampton says the letter, despite its stated intentions, hurts the case rather than helps it.
"There are victims out there still affected by this case we don't want to take away from the legitimacy of those cases," Hampton said.
The East Area Rapist, also known as the Original Night Stalker, terrorized communities in California between 1976 and 1986. His series of attacks began in the Greater Sacramento area.
The Sacramento County Sheriff's Department recently shared new leads in a double murder they believe was committed by the East Area Rapist in Rancho Cordova in 1978.
"The neighborhoods that received these letters were neighborhoods that were affected by the East Area Rapist," Hampton said.
FOX40 News is digging deeper on this case in a new podcast called Exposed.