Complex sentence: Mateen's wife is still under investigation, no arrests have been made, and no other motive of the attacker has been determined--officials have not confirmed the "speculation that Mateen lashed out because he was gay or had animosity toward gay or Latino people".
Split into simpler sentences: Mateen's wife is still under investigation, no arrests have been made, and no other motive has been determined. Officials have not confirmed the "speculation that Mateen lashed out because he was gay or had animosity toward gay or Latino people".