If you recently found a slip of paper from the police on your car windshield, it might not have been a parking ticket. Police have been warning the way you leave your car might cost you for another reason.

The Royal Newfoundland Constabulary is reacting to a big spike in car break-ins with an unusual public relations campaign. Police officers are placing a checklist on cars about what makes it attractive to a thief.

In February, the RNC inspected hundreds of vehicles in St. John's as part of its "Lock It or Lose It" campaign, and found that nearly half of them were vulnerable to break-ins.

Out of almost one thousand vehicles inspected during the campaign, the RNC found that forty-five percent were unlocked, had their windows down, or displayed valuables in plain sight.

Police carried out their inspections at sites such as the Avalon Mall, where officers spotted a lot of opportunities for crime.

"People are just not protecting themselves enough," said Sgt. Doug Day of the RNC Street Patrol Unit, after finding vehicles with wallets and expensive electronics in plain view through the window.

RNC Officer Doug Day

RNC Officer Doug Day inspects vehicles in the parking lot of the Avalon Mall, as part of the "Lock It or Loose" it campaign. (CBC)

"People say, 'I was only in the store for a minute,'" says Day. "Well, that's more than people need."

One group that will not be surprised to hear that such items are being left on display is the thieves.

During November and December of 2013, there were 320 car break-ins, or about five per day.

With potentially just as many going unreported, this rise in break-ins is what prompted the campaign.

Some people who received notes on their windshield said it was a habit they would need to break.

"I work with an electronics service and I have parts that I'm installing," said Stewart West, after the RNC spotted valuables in his vehicle.

"I was going to go in, install it and come back out. Basically, it needs to be a better practice I guess."