I seriously suspect this scarf is not a fashion statement. It seems to me to be a football (soccer for Americans) club scarf. If I was forced to guess, I'd say these are the colours of Celtic Glasgow, still popular among Poles in 2009 because they had Polish goalue, Artur Boruc, or some Polish clubs, Legia Warszawa maybe? Lechia Gdańsk? Lech Poznań? Hard to say.
I would not be surprised if at least one of the perpetrators is Polish. It reminds me a type of murder that occurs in Poland way too often, when a group of men, usually avid booze drinkers, not fond of hard work, but loving some fast cash targets a person that usually lives alone and is not very fit, so makes an easy target. The violence used is usually on horrible levels far exceeding what is needed to incapacitate or kill the victim. If there were any rumours of Alan having some hidden savings or riches then yeah, it is very very possible he was targeted by the type of perpetrators described above.