New Delhi, May 18 (ANI): The Delhi Police on Wednesday arrested four people for murdering 61-year-old doctor in southwest Delhi’s Palam area last week. Investigation officials said Balwan Singh Ramawat was shot dead by two contract killers hired by his wife’s lover, Hari Om. The police official said while both the killers have been arrested, a friend of Hari Om has also been taken into custody on charges of supplying the murder weapon.