The police (警察) government is full of police officers. This is the formal way to say "police officer." It is similar to 警官, but has a slightly more official feel to it.
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.
That police officer always says one word too many.
That policeman escaped in the confusion!
When the police officer found the suspect, he was painting a beautiful landscape on a hilltop.