My partner "shook down" a suspect, and after putting the cuffs on him I shook him down again before putting him in the car. My partner had missed the .25 automatic in his pants, but I fortunately found it.
The officer either didn't "shake him down", or did a bad job of it.
I was present once when a fairly combative female was patted down, the whole nine yards, transported, etc. When being searched more thoroughly at the holding facility it was discovered she had a large metal sharpened nail file with a handle on it taped to her bosom. Scary stuff. If she had been patted down properly it should have been found. I think everyone was a little squeemish to get close to her breasts and she was counting on that.
Sure pays to be extra careful.