A woman was killed by a spear to the chest at her home in Hallandale Beache, Florida, north of Miami, in July. Witness "Alexa" has been called yet another time to give evidence and solve the mystery. The police is hoping that the smart assistance Amazon Echo, known as Alexa, was accidentally activated and recorded key moments of the murder. “It is believed that evidence of crimes, audio recordings capturing the attack on victim Silvia Crespo that occurred in the main bedroom … may be found on…