MUMBAI — He is the revered father of Indian independence, and it was what would have been his 150th birthday. And yet, on Wednesday, vandals attacked a memorial to Mohandas K. Gandhi, painted “traitor” in lurid green across his picture, and may have stolen some of his ashes.

Police officials in Rewa, in central India, site of the memorial, said they thought it was an inside job because there were no signs of a break-in and the thick green paint defacing Gandhi’s picture was being used by workmen at the memorial.

Given Gandhi’s status as a titan of peaceful resistance, the vandalism might seem unthinkable. But it appeared rooted in the kind of Hindu nationalism that inspired his assassin in 1948, and which has been on the rise in India in recent years.

Chanchal Shekhar, Rewa’s inspector general of police, said that detectives were taking writing samples from the memorial workers to see if they matched the scrawl found on Gandhi’s picture.