Did Maedhros kill Laughter?

[Urwen]

Oh,yes. "Bye bye Lalaith I never liked you!"

Don't you care about her just a little?! For I do!!!!!

[Nerwen]

Originally Posted by Urwen

Oh,yes. "Bye bye Lalaith I never liked you!"

Don't you care about her just a little?! For I do!!!!!

Sure, it's a very sad part of Turin's story (as are most of the other parts). But I believe seven people now have already given serious answers to your original question. To quote just one:

Originally Posted by Eomer of the Rohirrim

It doesn't make sense to arbitrarily assign responsibility to some agent down the chain of causation on the basis of some positive, yet entirely unrelated, consequences of a later date.

Since your only counter-arguments have been that a.) Maedhros killed other people, b.) Lalaith might have been awesome had she lived to grow up and c.) she was cute, I don't think you can blame the rest of us for turning it into a joke.