Free Audiobook - The Two, by Will Carver and narrated by Richard Aspel and Nicki Paull, is free from Audible (Random House Audiobooks). There may be some geographic restrictions, but you shouldn't need a monthly membership to grab it.
The call comes at midnight. It looks like a tragic and petty murder - a rising star in San Francisco's legal firmament found shot in a dark alley. But for homicide lieutenant Abe Glitsky, the crime cuts horribly close to home - unknown to anyone, the victim was his daughter. Seething, Glitsky leans hard on his only suspect - a homeless heroin addict found lingering over his daughter's body, with her jewelry in his pocket and a smoking gun in his hand.
Free Book - Pets in a Pickle, by Malcolm D. Welshman, is free in the Kindle store and from Barnes & Noble (where it's the Free Friday selection), courtesy of publisher John Blake. It isn't free for those in the UK, but is marked down.