Well...I'm kinda lost on this one. He could have seen you make the turn and thought you were drunk. Most normal people stay in the center of the lane during turns. We, on the other hand, drive "normal."
He could have been bored. He could have thought you were drunk (in which case I would have followed for a few miles. But, had I not seen any indicators of someone driving while intoxicated, I would have called it a day after a few miles. Maybe when you drove by the accident, you were doing the speed limit. Officers like for people to slow down if they are on the roadway working. And, it's the law to either vacate the lane closest to the officer or slow at least 20mph below the posted limit. Did either of these apply to your situation? He could have been ticked off and decided to follow because you might not have slowed for them or cleard the lane. Or, he could have been bored.
Or, he could have been going in the same direction as you. I have left traffic stops, accidents, pulled out of driveways, and have just so happened to be going the same direction or to the same location as someone else. I have followed people for long periods of time, but only because I had to get somewhere. Usually, the only reason I will follow them for so long is because THEY WON'T GET OUT OF MY WAY!!!
There are numerous possibilities. The last...he was a jerk....waiting for you do screw up. I hate those guys. I had an officer follow me
FOREVER out in Helotes. I pulled up to the exit of my neighborhood. I heard a loud bang from under my truck. The officer was turning around in front of me as I was making my right turn onto the hwy. We drove for 5 miles and he stopped me at a gas station. I was freakin pissed. I couldn't figure out why he was stopping me. I was pissed and he knew it. He told me to chill out. I continued asking why he was stopping me. He said he saw me throw a beer bottle out of my window (hence the thump I heard from under my truck). I was pissed and told him he did not see me throw a bottle and he knew it. If he said I did again, he would be lying which goes against everything he stood for. I was FUMING. Then, looking at the front of my truck, I notice something. One of my four KC lights is missing.....Hmmmm..... Guess what the thump was under my truck....
Now, I was not only pissed, but upset I lost a KC. I calmed down a bit, apologized to the officer (he was waiting for a safe and well lit place to stop me), and went back to my hood where I picked up my trashed KC light.