When an ordinary home in Denver is burglarized, they have you fill out a police report, perhaps make a cursory glance at the scene, and that is about it. But, when the chief of police's home is burglarized, the crime lab dusts for prints, the prints are compared to records, addresses are followed up on, possible directions of flight are discovered and arrest warrants are issued.
Peter Lewis, the 20 year old man named, very likely is a burglar who made the mistake of robbing the wrong house. Of course, there is absolutely nothing wrong with carefully investigating a routine burglary and tracking down the person who did it. Indeed, the success of the police in this case makes a strong argument for beefing up the investigative resources of the police (which must devote most of its resources to things like traffic enforcement and routine patrols and responses to 911 calls) and investigating a much larger proportion of crimes.
The death penalty or any other harsh sentence for crimes, does little to deter crime, since people who commit crimes don't expect to be caught and most of the time, they're right. But, increasing the chance that a criminal will be caught could have a very significant deterrent effect.