LOS ANGELES, California (CNN)  -- A man who Los Angeles police believe raped and murdered dozens of women decades ago was arrested by cold case investigators this month after a computer matched his DNA to evidence from two killings in the 1970s. John Floyd Thomas Jr. may have begun his killings as far back as 1955. John Floyd Thomas Jr., 72, may have begun his killings as far back as 1955 and he could be one of the worst serial killers in United States history, according to Los Angeles Police Chief William Bratton. "We have yet to reach the depths of what he has done," Bratton said Thursday.
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Police say John Thomas Jr. may have begun killing as far back as 1955
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Thomas arrested April 2 and is charged with killing two women
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72-year-old could be linked to dozens of other killings and assaults
Until his April 2 arrest, Thomas was a @placeholder insurance adjuster.