In the USA, the Dylann spelling with two Ns wouldn't go over well. In the immediate after math of 9/11, I wouldn't have wanted to be named Sadamm since most Americans only had one powerfully negative association with the name. In general though, I think of notorious perpetrators by their last name (Bundy, Dahmer, Manson). A lot of famous killers in the US had very common or of the period names (
Ted,
Jeff,
Charles), so they aren't the only associations people have with the names. Nearly everyone knows a
Jim, so
Jim Jones isn't going to be the top association.
Until recently, I would say that
Dahlia was too associated with the Black
Dahlia murder victim for most people to consider using it. I think the memory of the case is fading now.
Meredith seems to have been uncommon in Italy before the case, so it makes sense that it would be the only association people have with the name.