Police in the Chicago suburb of Wilmette said they are "seeking to check the wellbeing" of Irish singer Sinead O'Connor, who they said has been missing since early Sunday.
Police declined to confirm that they were looking for O'Connor or searching for her whereabouts.
O'Connor, 49, reportedly left the Wilmette area for a bicycle ride at 6am (local time) on Sunday and has not returned, the police said in a statement. A caller expressed concern for her well-being. Police said they did not know O'Connor's connection to Wilmette.
Representatives for O'Connor could not immediately be reached for comment.
Last November, the singer received medical treatment after a message about her taking a drug overdose was posted on her Facebook page.
Earlier this month, comedian Arsenio Hall filed a $5 million defamation lawsuit against O'Connor, who accused him of supplying drugs to rock star Prince, whose death on April 21 has prompted speculation about an overdose.
O'Connor, whose biggest hit was her 1990 version of the Prince song 'Nothing Compares 2 U', posted a note on her Facebook page claiming Hall supplied drugs to Prince for years.
Before her disappearance, the singer posted a bizarre message addressed to her son on her Facebook page, which has more than 600,000 likes.
Reuters / Newshub.