During the witch trails Mary warren is bored and starts making a poppet in the court room. Abigail who is near he takes notice and begins to plot something on taking care of Elizabeth
When Mary Warren had left the poppet unattended, Abigail saw this as an opportunity to put her plan into actions. Abigail punctures the poppet's stomach with a needle and then leaves it there for Mary Warren without her suspecting a thing
Later that same day, when Abigail was having dinner with Parris she collapsed on the floor from pain. Later we'd discover that there was a needle lodged into her stomach that was causing this immense pain. She would further go to blame Elizabeth for this with the accusation of witch craft
At the night, same day of the trail, Cheever goes and detains Elizabeth on charges of witch craft. The evidence he found to prove this was a poppet that Elizabeth was gifted from Mary Warren which had a needle lodged in it's torso. This was proof enough for the people since Abigail accused Elizabeth of this kind of witch craft and it was seemed to be true