Aggravated Assault - False Report

My question involves criminal law for the state of: Tennessee

My son was recently arrested on an aggravated assault charge.
Details: A person claimed my son and his friend (her ex-boyfriend) broke in to her house and stole a 52 inch tv, ps3 from her living room and money out of drawer in the bedroom. This person happens to live in a somewhat busy area and there are no witnesses to respond to her allegations. Her now boyfriend approached my sister at work and told her he knew it was her nephews that broke into his girlfriend's house. Granted, my older son is away at college and at the time this was going on my son was at home with me and my husband. After realizing this, he told my sister that he knew it was my younger son and his friend (his girlfriend's ex-boyfriend) that broke into the house and he wanted the items brought back. Later the next day, we heard rumors of someone else committing the crime. With that all said and done she and her boyfriend are harassing everyone that they have named. My younger son got tired and approached the girl, pointed to her and told her to keep his name out of her mouth because he didn't do it and he was tired of her lying on him. My son is 6'4" 330 pounds. The girl had charges brought against him -- aggravated assault. No weapon was found on his person. No one has seen a weapon. A day or two later my older son calls me from college and tells me he has been talking to the girl on myspace and she told her who actually took the items from her house -- her ex-boyfriend -- my younger son's name is not mentioned.

Now, this incident happened on a Tuesday night, the warrant was completed on Wednesday, my son was arrested on Friday and on the warrant it said arrested for an outstanding warrant. I don't know much about how things are supposed to operate, but why did the warrant say outstanding when we knew nothing about the warrant in the first place?

If this happens to get thrown out and/or my son is found to be not guilty what kind of charges can be brought against the girl and/or her boyfriend for 1. harassment and 2. false police report.

Your son needs to get help from a lawyer. His lawyer will help figure out what she said to the police that triggered an "aggravated assault" charge.

A warrant is "outstanding" between the time it's issued and the time it's executed.