This is not what that report says. This is a similar framing to what people used to attack the attempt to repeal the 3 strikes law in California.
Now if you want to show me that people were released who were CURRENTLY detained for rape, theft, etc, etc, I'm interested to hear about that as it's a problem. If you're just telling me that people who had previously been convicted of a crime were released... uhmm... who cares?
If a resident alien commits murder then they have a hard time renewing their green card and are subject to deportation. This also includes being convicted of more than one deportable crime, drug crimes, firearms offense, fraud, etc.
So here we have these illegal immigrants, convicted awaiting deporation hearings, then they are let free. First off, the U.S. doesn't even really know who these people are. They have fingerprints now, but that is it.
So a lot of sensible people are really concerned.