Anne Lamott in Bird by Bird has an essay about calling people who know things. I've done this a number of times and probably should have done more. I did spend a lot of time talking to those who know things I need for my books.
Many of my books concern doctors and nurses. Since I worked in hospitals and am married to a doctor I've found this easy. I once had a doctor sit down and draw diagrams for where a person should be hit on the head to produce the kind of amnesia I wanted one of the characters to have and how to trigger her memories in time to help the heroine.
Some of my calls to experts have resulted in amusing stories. I was writing one of my mysteries and needed to know when the funeral could be held on a murdered victim. The funer played a large role in the story. My daughter had a friend who was a cop. I used his cell number and left a message. This young man had been a many times visitor at our house so I knew he would call back. He did. I'll try to reproduce the conversation.
Mike _ Ma, is there a problem?
Me - I just murdered this woman and I want to know how long you'll keepthe body before the funeral.
Quick and to the point.
Mike - No, No. She didn't. She's a writer. This is a mystery, Ma?
Then he gave me the information I needed. I will laugh about this forever.
So when you need facts for the story you're writing and you don't know the answer, call, visit or email the people you think might have the answer. Just don't forget to tell them you're writing fiction.