I recently read a blog which discusses research in writing mysteries and doing real-life research in the field.
Here’s my comment:
Research in a novel is an iceberg. There's a lot more under the water than is showing. Insert metaphor here about the book being the Titanic if that research is wrong.
The more the research appears on the page in the form of your main character/s, the more you need personal experience. You can fake a SCUBA scene with research but not an entire book if your character spends a decent chunk of the novel underwater. If needs must, have an expert read your book.
If your personal life experience doesn't remotely connect with police work, a police procedural probably isn't the best mystery subgenre to write. An amazing variety of mystery types and main characters are out there, and your own life experience and interests can enrich your books. Find a genre that fits. Your own emotional references should be considered, as well. You may very well regret spending months or years in the viewpoint headspace of someone who is your polar emotional opposite.
WORST RESEARCH SOURCES: TV shows and novels.
A RESEARCH SOURCE I LIKE: If you need to write horses, Judith Tarr's column at Tor.com. Search the label with her name or "SFF Horses."
THE MOST INTERESTING OVERHEARD RESEARCH: Many years ago, pre-9/11, Mom and I were at a hotel restaurant on the NC coast, and the room was full of high-ranking officers of all the military branches, and they were chatting away about military things that should not be said in public. I wasn't stupid enough to ask them questions and would never use that info, but dang!
THE BEST ANSWER I HAVE EVER RECEIVED ABOUT WRITING FIGHT SCENES FROM A FEMALE VIEWPOINT:
Years ago, I had a chat with a weapons and combat expert about fighting. (Science fiction and fantasy conventions are filled with military, police, and scientists who love to answer questions.) I asked him who was the most dangerous opponent in a one-on-one physical fight.
His answer-- “In a bar fight most men will keep fighting until they go down. Later, they’ll get up, and we might have a beer together. A small man doesn’t do that.
“To him, it’s not a fight, it’s survival. He’s fighting to kill because he knows he might not survive otherwise. If he goes down, he doesn’t stay down. He comes right back up and keeps fighting until he takes you down.
“He’ll use any weapon he can find to kill you, too.
“Never pick a fight with a small man.”