Visible crew/equipment: Immediately after the sheriff hands over his revolver, the moving boom microphone becomes visible as it is reflected in the map behind the mayor, below the words "Cabot Cove." (00:25:22)
Visible crew/equipment: When Carmine lies dead, a studio light is reflected in the bureau's mirror in front of him.
The Return of Preston Giles - S7-E7
Visible crew/equipment: When Preston leaves Jessica at the hotel, a large set light is reflected on the right side of the car. It disappears in the reverse shot.
Visible crew/equipment: When Clarence recounts the events of the night of the crime, a T-mark is visible on the floor.
Visible crew/equipment: When the sheriff exits the gym carrying the bottle, rigs and filming equipment are reflected in the window behind him.
See You in Court, Baby - S7-E3
Visible crew/equipment: When Briscoe visits Dennis, multiple set lights are reflected in his lenses. These reflections cannot correspond to practical fixtures within the house, as no such light sources are visible in the reverse shots.
See You in Court, Baby - S7-E3
Visible crew/equipment: When Dennis finds Marcia in the house, he sits down and she follows. The shadow of the boom microphone can be seen moving downwards on the wall behind them.
Answer: In a flashback scene, it was shown that he had a violent temper, so it stands to reason that he finally killed her in a fit of rage.