sorry. Of course there is the possibility that the graphics were added in aftermarket.
I would recommend he shows pictures of the different body syles of ford focus and escort available from 91+. Stick to 4 door sedans and 5 door hatchbacks both.
Anything ealier than that and a person would have a harder time distinguishing it as ford, not only that but the likelihood of someone adding those types of graphics or purchasing it with those types of graphics from a dealer would be extremely low.
Please note though, that he should add in early 90s J-body cars like the cavalier and early 90s dodge spirits as well. I dont think he would have to worry about neons, as they are fairly easy to distinguish as a unique look to dodge, however the cavalier and dodge spirit are vehicles that I often see some degree of confusing involving. Not only that but those are the most likely candidates for that type of graphics package.
If the witness is unable to pick a similar car from that lineup, then I am afraid that the search will be fruitless. However, it may be possible that as I said earlier, the witness's memory is unreliable, however your brother, I am sure as a police officer, is aware of the inherent problems in line-ups.
Good luck