Well, crimes are committed by convicted felons probably every minute of every day. That's because we release people from prison, including illegals. I'm not sure why it should be shocking that drunk drivers who are illegals are released from prison, when citizens are arrested by the dozens in my city every weekend night and few spend more than the evening in jail. I suppose we could jail them all till deportation, but we'd have to build a lot more prisons, and then pay maybe $30k/year to house them all. What's a few $billion more per year to house more prisoners?
The article explains why 3/4s of the murderers were released - the Supreme Court requires their release. As to the remainder - we're VERY good at imprisoning illegals who commit crimes in the U.S. Roughly 1/4 of our Federal prison population is foreign born, some unknown percentage an illegal immigrant. But we can and do imprison 10s of thousands of non-citizens. So it's not very likely the 'convicted murderers' were people who shot their wife, was picked up by ICE, then released because Obama [something something]. Hard to tell from the story because they didn't try very hard to find out why we'd release murderers when we have the largest prison population on the planet, and imprison more per capita than any country on the planet, including without hesitation non-citizens.
I guess the answer is build more prison? Could be. The prison lobby pushed very hard for 3 strikes laws and for the 'papers please' laws in AZ and elsewhere. Growth industry!
I suppose we could hold them all indefinitely for years, or we could just do the deportations without hearings - round up anyone who looks like an undocumented and bus them to Mexico City or something.