In: Psychology
To investigate the theft it is important to gain knowledge from the locals, It can be done by chatting with the locals, whether they saw any unknown person in that vicinity, whose action can be doubtful.
Then visit the place where the theft had taken place. The chances are that a local person may be involved in it. Gather all the information by minutely observing every person and their body language.
Driving a car when there is snow on the ground is difficult thus driving the car when there is no snow is easier.
At one scene the officers found the debris that is consistent with parts of a convertible top. As an investigator, I would Identify, gather, and preserve the evidence.
To establish reasonable ground I would find out how many people in that locality are well versed with the changing of cars looks. As no one has seen anybody coming and stealing the car the person must be from the same locality, who knows about the cars or a juvenile in bad a company who knows about the activities of the resident of that locality and who can keep watch on them.
It is important to establish the background of the suspected after the interrogation of the people staying in that area to focus on a few as a suspect.
From these doubtful people, it would be easier to find out their activities, and connections. The person may be just stealing the car and delivering it to some garage owner to convert and sell it.
The only evidence is the presence of debris, it is important to know is there any garage nearby that does modification of cars. It is important to investigate the garage owner and employees
If it is there then how many cars he had modified recently.
If he can give details of the cars modified or painted it will easier for the investigator to establish a link.
Secondly, the thief would try to dispose of the car as early as possible for that he had to produce evidence of ownership, being a thief he would be having a forfeited bill of purchase, and he will change the license number plate to avoid identity.
But the thief cannot change the engine number it is easier to identify the car owner from the engine number.
Thus starting the investigation from the locals, and by sorting out the suspects, the investigators would try to find the background of the person shortlisted, and zeroing on the suspected person can lead to arrest.