The police were alerted by neighbours, whom the daughter of the couple had called over the telephone from Delhi after repeated calls to her parents elicited no response.
Mehra had retired from Dena Bank as a cashier last year; his wife worked as a labour enforcement official (LEO) in Barabanki, on the outskirts of the state capital.
When the police forced their entry into the house late Sunday, they found fresh blood spattered all around. The body of Mehra lay on the floor near the dining table, while his wife's body was on the sofa in the drawing room.
Police said prima facie it appeared to be an attempted robbery. There were signs of physical resistance by the couple, as the intruders may have tried to overpower them.
Some valuables were found strewn around.
The couple was last seen taking their regular walk with their pet dog at around 9 pm Sunday.
Police found the pet locked in a room of the house.
Mehra had been stabbed 16 times; the woman had 28 deep wounds and gashes, police said.
"There are clear signs of brutal attack -- the kitchen knives used in the attack were found broken," a policeman told IANS.
The couple is survived by a daughter, Gunjan, who works in Delhi.