The final indignity

In a little less than three years from now, the killer will sweep away the pile of flowers on the grave, left behind after the memorial service.
He picks up his shovel and begins to dig.
The shovel strikes something. He taps. Twice.
He breaks the vault, leans up the coffin, and rips it open.
Her.
“Hello darling,” he croaks. “Missed me?”
Then, he lights a candle, sticks it in a cupcake, and places it in her rotting hands.
A gravely “Happy Birthday” echoes across the moonlit graveyard.
He checks his watch. Then the headstone.
“You’re legal now,” he grins.