Either a lot of details are left out or the police are up to some bullcrap. In order for her to be charged as an accessory, she had to set him up for a beating, participated in the beating, met with this guy with her boyfriend knowing he intended to harm him or another crime was committed in which she was involved. An example would be a drug deal or financial transaction gone wrong. Then they decide to press charges against her because they saw her in the car with her boyfriend two weeks later? That doesn't make sense.
A lot of details are left out. I found the same court records. I'd cut and paste if I could, but they're PDF's of scanned documents. Here's my summary of the warrant with no omissions:
Police were called to investigate an assault at TP's residence.
They found a guy badly beaten, later identified as a friend of TP's, and had him transported to the hospital.
They interviewed TP, and this was what she said:
She was arguing with her BF on the phone.
She assumed he wasn't coming over, so she invited her friend/neighbor over to hang out and play cards.
They fell asleep in chairs on her patio.
TP awoke to find her BF kicking and punching her friend.
Her BF then fled.
TP said her BF was a very jealous person.
TP locked herself in the bedroom and stayed on her phone with her friend.
TP said the last she saw of her friend, he was crawling off the patio towards his residence.
When asked why she hadn't called the police, TP said she was afraid.
Police advised TP that they had probable cause to to arrest her BF, and if she assists the BF in evading law enforcement, she would be criminally charged.
An arrest warrant was obtained for the BF on the violation of Attempted Homicide without Premeditation, and turned over to the U.S. Marshal.
The Marshals arrested the BF in the presence of TP. They were found together in TP's mother's car. Investigation found that TP had not been at her residence for several days prior to the arrest. Based on the warning given to TP regarding assisting her BF, and TP's acknowledgement that she understood, a warrent was obtained, and she was subsequently arrested as an Accessory after the fact.