Police in Phoenix release new information about two serial killers blamed for at least 11 murders since last year. A total of at least 41 people are believed to have been attacked by the pair, who operate separately.

According to the police documents, the "Baseline Killer" shoots his victims in the head - and has been active since September. And the "Serial Shooter" is a sniper who has been killing since May of 2005.

The town has been on edge since word spread that one or more serial killers could be on the loose.

Clear Channel Outdoor revealed a plan for informational billboards about the killings, and the civilian patrol group the Guardian Angels has increased its efforts in Phoenix. Since arriving last week, the group's members are now patrolling parts of southeast and eastern Phoenix.

Michele Norris talks to Renee Gutel from member station KJZZ.

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