A Muslim man accused of killing a cow was beaten to death by a mob in central India, police said Sunday, the latest vigilante murder over the animal considered sacred by Hindus.Siraj Khan, a 45-year-old tailor, was attacked in the Satna district of Madhya Pradesh state early Friday and died at the scene, local police official Arvind Tiwari told AFP.Kahn's friend Shakeel Maqbool, who was also attacked, was admitted to hospital with critical injuries.As details of the violent assault emerged at the weekend 400 additional police were deployed to the district late Saturday as inquiries widened, the Press Trust of India reported."We have arrested four people, and they have been sent to judicial custody. We are investigating what prompted the attack," Tiwari said.He added that meat and a bull carcass was found at the scene, but did not elaborate as investigations were ongoing.Hindus consider cows sacred and slaughtering the animals, or possessing or consuming beef, is banned in most Indian states.Cow slaughter in Madhya Pradesh carries a maximum seven-year jail term but many other parts of India impose life sentences for infringements.Prime Minister Narendra Modi's ruling Bharatiya Janata Party (BJP) has promised to completely outlaw cow slaughter in India.The right-wing Hindu BJP has been accused of turning a blind eye to a rising number of vigilante attacks in the name of cow protection.Rights groups say Hindu mobs have been emboldened under the party, who stormed to power in 2014. Many of the victims are Muslims.In two prominent cases last year, a dairy farmer was killed on a roadside for transporting cows and a Muslim teenager accused of carrying beef was stabbed to death on a crowded train.