Searching for something to read on this site, I bumped onto this...real pleasing to read this as an old car nut.
prescriptive on a car nut specializing in old cars...
Keys:
They did not indicate what type of keys he had on him upon discovery, but if they are all automobile keys, then it's most likely a car thief of any caliber. If not, he probably acquired them along with the clothes and library books.
Car keys then were ridiculously simple. They only have about five cuts for almost all makes. Ridges rarely were deep. You have about 20% chance of having your key work in another car's locks (as long as the makes were same, i.e. Ford/GM/Mopar). Similar cuts from the ridges could work with some fine jiggling. My father's old keys to his Chevy worked on my neighbor's Caddy. What small-time car thieves at the time would do is to go to a junkyard and take all the keys they come across then try key after key until one works. They also can file down a blank key just a little and jiggle/bump.
I agree it was an unexpected opportunity when he saw that '62 Catalina. By the '70s, cars were coming with new security/safety features. Door locks, locking steering wheels, ignition cylinders relocated to steering column, locking transmission shift lever, etc. That added time. The thief could have been intimidated by all this and decided to case for an old car (easy target).
If the Catalina had a manual transmission, he knew he found the jackpot. Laughingly easy to steal one of those things - push the car out, hop in, and start it in gear as it's rolling down. You didn't need anything (no keys, no tools, nothing) to grab it. A manual was much better to push-start than auto in these days.
After reading the reports, the owner stated he woke up in the morning to find his car gone. I don't know the circumstances, but wouldn't he hear his own car starting up and driving away? I suspect that's exactly what I thought happened.
In one of the reports, an officer tagged the john because the headlights were dim. The dim headlights tell me the car was running off the battery as the generator/alternator wasn't keeping the battery replenished. He had to be driving a good while when the officer attempted to pull him over. This is telling - the john stole the car without using a key. If the ignition was used, the ignition would be in RUN position. The corresponding wiring from being in the RUN position would enable the generator/alternator to charge the battery, keeping the headlights bright.
All this behavior indicated the john needs to be somewhere, fast. I think he was on the lam.