Sinead O'Connor Goes Missing in Chicago After Posting Cryptic Facebook Messages

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Sinead O'Connor has gone missing after reportedly leaving for a bicycle ride in Chicago at 6 a.m. on Sunday, Wilmette, Illinois police tell ET.

Law enforcement received a call to check into the well-being of the 49-year-old singer, but no other information has been given.

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At 8:12 a.m. CDT on Sunday, O'Connor posted a cryptic Facebook message to her oldest son, Jake, asking him to take custody of her third child, Shane.

"Jake, kindly go to the court on Tuesday and take custody your brother from Tusla," she wrote. "My lawyer will be making the illegal way yourself and Donal got him into Tusla (lying to the cops etc) known to the judge. Expect to be in trouble. In fact, you'd best bring a lawyer of your own. And do not abandon your brother or any other of my babies again. What you have done to your brother and your mother is LITERALLY criminal."

On Friday at 4:00 p.m. CDT, O'Connor also posted an open letter to Shane. "Baby, I've been trying to get you out of care but Tusla are being monsters. I have to back off because they are hurting me so badly. I get unwell again if I go near them," she began her post. The best thing I can do is advise you to get a solicitor of your own -- which you are now entitled to because you are 12 -- and bring a case of your own against Tusla, under the children's rights clauses of the constitution."

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"You want to be with your mother and you're being prevented. Your mother is being bullied so badly by Tusla [that] she can't manage your release. Your lawyer will have to do it for you," she continued. "If no one wants you to come to me, then insist on going to Jake. You deserve better than the way you're currently being looked after."

After writing to Shane, O'Connor announced on Saturday afternoon that she was planning on attending a protest out of state. "Heading Down South for several weeks now," she wrote. "Hoping to begin 'Piss Where You Sit' protests in North Carolina. Irish style. ‪#‎FreedomPiss"

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The search for O'Connor comes six months after the "Nothing Compares 2 U" singer was hospitalized following a lengthy Facebook message indicating that she may have overdosed. She also shared a NSFW message calling out several people who she felt had wronged her.

"Jake, Roisin, Jr., Frank, Donal, Eimear, I never wanna see you again," she wrote at the time. "You stole my sons from me. Then you had hypocrisy to come to hospital and then not be here when I wake and not pick up phone? I'm sh*t to you. You're dead to me."

ET will have more on this story as it develops.