sentence coreection doubt

if " army believes " then why " police believe "…plz somebody clarify…

if " army believes " then why " police believe "...........plz somebody clarify...

There is speculation that increasing cold weather was what may have been responsible for the Anasazi move from Mesa to Sites in other canyons.

1 that increasingly cold weather may have been

2.that increasing cold weather was what may have been

Which will be the correct one. Please give an explaination.