Complex sentence: In late 2012, A5 pod was sighted without Havannah (A28), as she was not encountered by the summer of 2013, she is now considered dead by researchers.
Split into simpler sentences: In late 2012, A5 pod was sighted without Havannah (A28), suggesting she has died. If she is not encountered by the summer of 2013, she will be considered dead by researchers.