Spooky break in

A couple of days ago, a filthy thief stole my nice JVC KD-LX10R
autoradio out of my 156 2.0 (02/2000). Lucky enough, there was no
scratch on the car, no holes underneath the door knob, no windows
smashed, nothing at all. The thief even removed the radio so neatly,
there were no marks on the dashboard or cables cut. My CD's were still
in the car, so were my sunglasses and fresh granny smith apple. The
weirdest thing was, that I found my car locked on the street (oposite
my house!), at least that is what I think: I used the remote control
and heard the car make just one clicking sound, after which the doors
were open, so I assume they must have been closed before. Also I am
convinced that I locked it earlier.

I am wandering how they came in. Could it be possible that there is a
universal key, or that my remote control was tapped somehow? Is there
anyone who recognises this? I think it is terrifying people can just
enter my car as they please. (I know, having a nice brick can be
enough for free admittance in any car, but still...)

Does this make any sence?

Regards,
Yaddha - Black 256 2.0 Lusso / 2000