A man has been arrested on suspicion of murder after a pensioner was found stabbed to death and set alight in her own home in Cambridgeshire.
Widow and former post-mistress Una Crown was found dead in her bungalow on Magazine Lane, Wisbech, on January 13.
Cambridgeshire Police said a 58-year-old man had been arrested on a suspicion of murder. He is being held in custody.
A Crimestoppers reward of up to £10,000 has been offered to catch Mrs Crown's killer.
A post-mortem examination found the 86-year-old had been stabbed several times and detectives believe the suspect set her clothes on fire to destroy evidence and conceal her injuries.
The motive for the attack is not yet clear, officers said.
Mrs Crown's niece, Judy Payne, 69, paid tribute, saying the family had been "shocked and deeply saddened by Aunty Una's death and cannot understand why anyone would want to hurt her".
She added: "We desperately want justice for Aunty Una. Whoever committed this terrible crime needs to be caught."
Mrs Crown was last seen alive on January 11 and made a phone call to a friend the following evening.
She had lived alone since the death of her husband, Jack Roland Crown, in 2009.
The couple had no children.