Who is lying?

The Smith family is a very wealthy family that lives in a big, circular home. One morning, Mr. Smith woke up and saw a strawberry jam stain on his new carpet. He figured out that everyone who was there that morning had a jam sandwich. By reading the following excuses, figure out who spilled the jam.
Billy Smith: I was outside playing basketball.
The Maid: I was dusting the corners of the house.
Chef: I was starting to make lunch for later.
Who is lying?