The Hub police are the law enforcement of the Hub, headed in 2161 by Sheriff Justin Greene. Most of them are simpletons who have a badge only because nobody else would take it. Their officers are spread throughout each district except for the Heights, where Mr. Hightower's guards have to fend for themselves. They also patrolled in large numbers around the Hub in the wasteland, ensuring that the caravans come to the Hub. The police station is in the downtown area, but if any member of the Hub police is attacked (those in the wasteland included), all others will become hostile towards them.
In fact, if the police become hostile, the Vault Dweller won't be able to leave the Hub (even if every single person is dead) without being in combat mode. Keep in mind that defeating every member of the Hub police is a remarkable feat - they make up for their lack of training with automatic weapons and good armor.
Sheriff Justin Greene runs the Hub police, and Deputy Tony Fry is his right-hand man. Tony Fry watches things near the entrance of the Hub, though Justin Greene and Deputy Kenny are both in the downtown police station, with several other guards. Even though Deputy Fry claims to be the sheriff's right-hand man, Deputy Kenny appears to have a much stronger bond with the boss. If the sheriff dies while the Vault Dweller is helping the Hub police kill Decker, Deputy Kenny is distraught.
Weaponry and armor
The Hub police have a variety of weapons at their disposal, usually combat shotguns and assault rifles, and wear metal armor and combat armor. Zack of the Gun Runners in the Boneyard claims that the Hub merchants go up to them and barter when they can get past the deathclaws, suggesting an outside source of their arms.
After receiving the Dispose of merchant or Dispose of Jain quest from talking to Decker, the Vault Dweller can report the crime to Sheriff Greene. If the crime has already been committed, the sheriff will be suspicious, but the Vault Dweller can talk their way out of it and the sheriff will offer for them to go along with him and take out Decker and all his guards in the underground hideout. The Vault Dweller will be given 300 bottle caps to start, and awarded an additional 1,000 when the duty is completed. The quest is never officially entered into the Pip-Boy.
Behind the scenes
One of Justin Greene's dialogue files is a reference to the show South Park, where one of the main characters, Kenny McCormick would (frequently throughout the show) die, and one of his friends, either Stan Marsh or Kyle Broflofski would say "They/You/I killed Kenny!" And the other, or the same one would say "You bastards!"