The DA didn't tell him? Yes, the old "nobody told me" excuse. Surely he is allowed to ask. I wonder how far that would go as a defense before this same judge. It seems that "ignorance" is an excuse if you are connected to law enforcement, a judge or a prosecutor but not for us "civilians."
It is the prosecutors responsibility to inform the judge. The Judge is not supposed to do the prosecutors job. The prosecutor only asked for $25,000 bail. $2,500 bucks would have freed this guy even in the best case scenario. Your anger should be directed at a prosecutor who did not make sure this creep was kept in jail. That is who should bear your scorn.
How hard can it be to find out somebodys criminal background? There is no national database for registered sex offenders, but is there one for convicted felons?
I realize it is tempting to jump on the "judge is a moron" bandwagon, but in the US of A, the judge makes decisions based on what the prosecutor and defense attorney tell them. They can't ask questions of the defendant. It is the prosecutor's responsibility to bring it up at hearing what the defendant's prior behavior is to mitigate being held without bond. If the prosecutor doesn't do his/her homework and know about the defendant's prior record, stuff like this is going to continue to happen. And since the prosecutor only asked for $25,000, I'll bet they didn't do their homework.