I’m trying to remember the name of a book I started once that I’m thinking of finishing. It was fairly new and I don’t think it was more than one or two decades old. (The book was published in the past two decades.)
It took place in a futuristic city and it was mainly a murder mystery. One of the things I remember distinctly is there was something about when the police caught someone, they didn’t use handcuffs but instead put a ring on the person’s head (called a halo) rendering the person passive.
There was also another element about a space probe traveling in space. I remember the probe was leaving relay beacons behind itself to contact earth.
Edit: The halo thing wasn't a major plot point, and may not have even been called a halo. I just remember there was a police raid at a fancy apartment and the guy caught really didn't want the ring thing put it his head because it made you completely helpless.