Police have linked the home invasion in a quiet Dartmouth neighbourhood last week to a second armed robbery at an East Preston home, the CBC has learned.

It was the second robbery that led police to the two 15-year-olds who have been charged with robbing an 81-year-old man. They allegedly knocked on his door at random last Wednesday, pulled out a gun, threw him to the floor and stole his car keys.

The teens appear to taken the car for later use as a getaway vehicle in the second robbery. In the hours following the home invasion, Halifax Regional Police and RCMP were searching for the man's missing black Buick Lacrosse with veterans' plates, when they received a call about the robbery in East Preston, on the outskirts of the city.

The description of the car used by the robbers matched the vehicle stolen from the 81-year-old man earlier in the day.

Hours later, that car was found abandoned on a dead-end road in nearby North Preston. The house in East Preston that was robbed was monitored by several high-quality video cameras. Those tapes, and evidence police found in the abandoned car, led police to the suspects within hours. They raided three homes in North Preston and arrested five teens.

Two 15-year-olds are charged in the home invasion. They, and two other teens are also charged in the East Preston robbery.

One of the 15-year-olds asked for bail when he appeared in court Monday, but the judge denied it, saying the home invasion was too serious a crime, and the risk to public safety was too great.

All four teens will be back in court August 16 to face their charges.