Richard "Ricky" Babbage was the younger brother of Brian and Amanda Babbage, all of whom were potential heirs to their late father's very substantial fortune. All three siblings were well-provided for, enough that Ricky never had to work a day in his life (and struck most persons as a spoiled brat).
Their father, either out of senility or just pure spite, changed his will constantly before his death, laying the ground for a very nasty legal battle between the three siblings, each of whom had enough to hire a battalion of lawyers. While Ricky and Amanda eventually agreed to a settlement, Brian refused, believing that he was entitled to a much larger share.
When Amanda was killed by a mail bomb, Ricky felt guilty, since the last time he had seen his sister, they had had yet another fight about the estate. Since the only other person with a motive, Brian, was in a coma, the ATF immediately suspected Ricky. He was grilled extensively, but the SFPD, backed up by Adrian Monk, didn't believe Ricky was the culprit. Without their support, the San Francisco District Attorney refused to indict Ricky, and he was released on bail.
Meeting Monk and Sharona Fleming at his home, he invited them in and started to go through his unopened mail. Sharona warned him not to open any packages, and Brian retorted that "I'm not an idiot." Less than a minute later, he eagerly started to open a package, supposedly a shipment of genuine Cuban cigars from a buddy in Key West (he assumed it couldn't be a bomb, since no one knew Ricky got them, except his siblings). When Monk shouted out a warning, Ricky tossed the package away in a panic and ducked behind a pillar, leaving Sharona holding the bomb. Still hiding behind a pillar, Ricky called the police and relayed instructions from the bomb squad, while Monk defused the parcel.
With Amanda dead, and Brian arrested for her murder, Ricky was likely left the sole heir to the Babbage fortune.