Husband's shock over affair claims linked to British wife murdered in France / Murder of British mother Karen Carter in France investigated as grudge killing / Murder of British mother Karen Carter in France a 'crime of passion' / British woman, 65, found dead in rural France with 'deep injuries' from 'sharp object' as cops launch murder probe / French mosque murder suspect expressed desire to become a 'serial killer' in video / French police hunt killer of Muslim worshipper inside mosque / French police hunt suspected killer of Muslim worshipper inside mosque / Netflix documentary 'From Rock Star To Killer' looks back on landmark French domestic violence case / Femicide: French court sentences man who burned his wife alive to life in prison