Amazon is pushing back against an Arkansas prosecutor’s demand for information from a murder suspect’s Echo smart speaker, setting up another legal battle over investigators’ quest for technology-based evidence and American privacy rights. Benton County Prosecuting Attorney Nathan Smith hopes the voice-activated Echo — which answers users’ questions, plays music, reads news and connects to other smart devices — will provide information on how a man came to be found dead in 31-year-old James Bates’ hot tub.