@MolochHunter raised the question in this discussion.

October 8, 2012, Trump tweeted "Got to do something about these missing chidlren grabbed by the perverts. Too many incidents--fast trial, death penalty."

I did some preliminary digging and found:

Maybe this:

Sandusky's criminal trial began on June 11, 2012, at the Centre County Courthouse in Bellefonte, Pennsylvania.[3][4] He maintained his innocence.[5] Of the 52 charges, 4 charges were initially dropped, leaving 48. On June 22, 2012, Sandusky was convicted of 45 counts of sexual abuse.[6] Sandusky was sentenced on October 9, 2012, to a minimum of 30 years and a maximum of 60 years in prison.[7]

Although those kids weren't "missing"

Possibly this, but the timing doesn't exactly match up. It's hard to say what Trump might have seen about this in the local New York papers and news shows after the investigation reopened in May 2012.

On May 24, 2012, New York Police Commissioner Raymond Kelly announced that a man was in custody who had implicated himself in Etan's disappearance.[20] According to The New York Times, a law enforcement official identified the man as 51-year-old Pedro Hernandez of Maple Shade, New Jersey, and said that he had confessed to strangling the child.[21] He stated in his written confession to police, "I’m sorry, I shoke [sic] him."[22] According to a 2009 book about the case, After Etan, Etan had a dollar and had told his parents he planned to buy a soda to drink with his lunch.[20] At the time of Etan's disappearance, Hernandez was an 18-year-old convenience store worker in a neighborhood bodega.[23] Hernandez said that he later threw Etan's remains into the garbage.[24] Hernandez was charged with second-degree murder.[22] According to a New York Times report from May 25, 2012, the police at that time had no physical evidence to corroborate his confession.[25]

If anyone can figure out how to search New York and national news headlines from the first week of October 2012 for news about missing kids, we might get to the bottom of this.