In an open letter to college students ahead of the April 20th Boston Marathon cops are advising them to leave their bags at home, take the T -- and lock their apartments.

That third one has nothing to do with the annual run and everything to do with a spate of recent break-ins.

“Always secure your on and off campus housing units when you leave and lock the doors at all times. A significant number of recently reported house breaks to student housing have been through unlocked windows,” says the letter, if they leave during the festivities because of spate of recent break-ins through unlocked windows.

The letter, signed by Police Commissioner William Evans and Superintendent Bernard O'Rourke, also says there will be an increased number of uniformed and undercover officers along the marathon route. Cameras, according to police, have been installed along the Boston portion of the route. Observation points, police say in the letter, will be set up near the finish line in Back Bay to monitor the crowd.

During the marathon two years ago, two bombs went off near the finish line, killing three and injuring at least 260. Dzhokhar Tsarnaev was found guilty of perpetrating that crime last week in federal court. His brother -- Tamerlan -- is also thought to have been an architect of the bombings, but he was killed during a later shootout with police.

This year, spectators are being encouraged to leave large items such as backpacks and large handbags at home. Those items are not banned, but individuals carrying such items could be subject to search, according to police.

Newbury Street and Huntington Avenue outbound will be closed to traffic to make it easier for pedestrians to move around, said police. Traffic and parking will be prohibited on several streets leading up to the marathon and on marathon Monday, police said.

Police said all public drinking, open containers and intoxication will not be tolerated and congregating on rooftops, fire escapes and porches is prohibited.