It is difficult sometimes to confirm you have the right person under surveillance. 

They own no vehicle, they move around often, you have no photo, the claimant does not go on Facebook, and they have no known place of employment.

The man exiting a possible good location may be a roommate, a younger brother, or a friend. It has been known for a claimant to have a twin. 

You have to be very careful you have the right person. If a claimant chain smokes, but your claimant does not smoke at all, that is a big red flag.

There are ways to confirm the claimant is the claimant. 

The claimant attends his deposition or has a known medical appointment and shows up.

The problem with a known date for a deposition or medical appointment is the claimant will be warned by his/her attorney that surveillance will be issued. 

The claimant will now drive fast or slowly, do U-turns, or drive down a dead-end street. The claimant may change a medical appointment to an earlier time on the date he/she is scheduled. You arrive at three pm, only to find out the claimant changed it to 10 am.

The best is to place a claimant under surveillance right away when the incident is fresh. Most claimants are not thinking of hiring a lawyer to file a lawsuit.

Always let the private investigative agency know about the deposition or the medical appointment. Let the agent start his surveillance from the appointment location and go from there. 

This way you have positive identification, you know what they are driving or what vehicle they are passengers in, and where their residence is.