Around six men pretending to be patients entered Dr Shamim Ahmad Khan's nursing home yesterday and later barged into the upper floor where the doctor lived, police said.
According to the in-charge of Kithaur police station, the robbers first tied up the guard and, with only the doctor and a female relative of his present in the house at the time, threatened them into handing over cash and valuables worth lakhs of rupees.
When the robbers were fleeing with jewellery and cash, police managed to nab one of them at a picket, police said.
But before police could take him away, an angry mob which had gathered following the incident, caught hold of him and subjected him to severe thrashing, leading to his death.
Kithaur police said they would soon round up those involved in the robbery as they had managed to elicit relevant information regarding his associates from the nabbed gang-member, who identified himself as Amit from Muzaffarnagar, before he was attacked by the mob.