The person calling Mandan and Morton County residents claiming to be a sex offender has struck again.

Mandan Police Chief Dennis Rohr said a Mandan resident received a phone call from someone claiming to be a sex offender at 7 a.m. Tuesday. The phone number on the person's caller identification system matched the number used to make similar prank calls to Mandan and Morton County residents over the weekend, Rohr said.

Another Mandan resident received a call at 5 p.m. Monday from the same phone number as the other calls, Rohr said. However, in that call, the caller told the woman who answered the phone that she would die within six days and did not say anything about being a sex offender, the chief said.

A Mandan man and a Morton County woman reported being called by a man over the weekend who claimed to be a sex offender. The caller warned the Mandan man to keep his children inside and claimed to be performing a sexual act on a child.

The caller told the Morton County woman he is a registered sex offender who recently moved into the community. He said police had ordered him to call everyone in the phone book, but police do not make such demands of sex offenders.

In the first two calls, the man gave the same first name but different last names. Law enforcement officials are not aware of any convicted sex offenders, registered or otherwise, with the given names.

Rohr said all of the calls were coming from the same phone number, which is that of a Bismarck-area cell phone.

The cases are being investigated jointly by the Mandan Police Department and the Morton County Sheriff's Department.

Anyone who receives such a call should notify local law enforcement authorities. People with caller identification should not erase the call information, and people without caller identification should call *69 immediately following the call.

Anyone with information about the incidents should call the Mandan Police Department at 667-3455, the Morton County Sheriff's Department at 667-3330 or Bismarck Area Crime Stoppers at 224-TIPS (224-8477).

(Reach reporter Jenny Michael at 250-8225 or jenny.michael@;bismarcktribune.com.)