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The "Nothing Compares 2 U" singer went on a bicycle ride in the Wilmette neighborhood on Sunday afternoon and hasn't been seen since, according to the site, and police were alerted and are currently searching for O'Connor.
A distressing message was posted to O'Connor's Facebook page last year, which appeared to come from the musician and said, "I have taken an overdose." According to TMZ, police are treating O'Connor as "missing suicidal."