Tackle the target from above
The Officer takes off in a run. You need to get after him. Thankfully it is not too hard to cut him off from an alleyway. When he ducks between the buildings, keep to the road and then cut to the right after the building. He should run right toward you and allow for an easy tackle.
If you are after a Full Synch that is a lot more demanding. Starting in an excellent position is imperative. Take off after him and when you get here:
Run on up the wagon and then set into the free running course. Just line up with the target and jump him to finish it out.