Sinead O'Connor Reported Missing; Alert Issued By Wilmette Police

CHICAGO (CBS) -- Sinead O'Connor was reported missing after she did not return from bike ride in north suburban Wilmette.

The singer left on a bicycle around 6 a.m. on Sunday, Wilmette police said.

"A caller has expressed concern for her well-being," police said.

No additional information was provided by police.

O'Connor had been staying in the north suburb, and collaborating with musicians here.

CBS 2 photo journalist Lou Kleinberg spotted her in the north suburb last week, and posted a picture on Facebook.

The Irish singer-songwriter is perhaps best known for her recording of Prince's song "Nothing Compares 2 U" and her appearance on "Saturday Night Live" when she tore a photo of Pope John Paul II during a live performance.

In November, O'Connor threatened suicide on Facebook and she has been involved in custody battles with her children.

This month, Arsenio Hall reportedly filed a libel suit against O'Connor after she accused him of providing drugs for Prince, who died on April 21.

O'Connor posted a message on Facebook hours before she was last seen on Sunday that appeared to be directed at her oldest son, Jake Reynolds.

According to the Daily Mail, she claimed Jake and her ex, Donal Lunny, had her 12-year-old son Shane placed in TUSLA, a child and family agency in Ireland.

Also this past weekend, she indicated on Facebook that she planned to travel to North Carolina to protest that state's transgender bathroom law.