Tabak was her neighbour as already said, but I don't know how long they had been neighbours.
But if it had been quite a time then they must have been on talking terms, it was Christmas time and Tabak's girlfriend was absent, and Jo's boyfriend was also absent, so maybe she did invite him in for a neighbourly Christmas drink.
It is a shocking sad case, but I can't understand why this particular murder has attracted so much media attention, after all murders are so common place these days unfortunately.
The police however are continuing with their enquiries into Tabak's background, both in the UK and also Holland, who knows he may be found out to be yet another vicious serial killer.