It has to be someone she knows if she was talking to friends 15 minutes before her car was driven near the bridge, parked, and the lights turned off.
What did she tell her friends she was going to do? If she said nothing, who was she with earlier in the evening?
Actually, that might not be true. Maybe she finished talking to friends, was bonked on the head, her car was driven to the bridge, she was ... taken somewhere else?
How did she end up 3 miles downstream 4 hours later with injuries inconsistent with suicide?
I love your question...what did she tell her friends she was going to do.
She was home alone and her husband was out at the movies until 11pm when he came home and went to bed. She was on the back deck texting, mostly with friends and family in California.