Flying to L.A. from San Diego, whatever the real world drawbacks may be, was a better option in the Columbo-verse. By dumping the body on his own lawn Ken was trying to reinforce the idea that the motive for the killing was due to Jim’s mafia research. As mentioned above, bringing police attention on his own home gave the already suspicious Columbo an opportunity to poke around. That’s when he noticed the opened mail, confirming his suspicions. Great episode.
Btw, how geeky am I to write: “a better option in the Columbo-verse”, lol