The four accused including the Nawada MP's bodyguard, domestic servant, apartment security guard and another accomplice entered his flat yesterday when he was away in Delhi, they said.
Singh, who is in Delhi for the Parliament session, was not immediately available for comments.
"It was a well planned theft. The arrested persons had inside knowledge about the valuables kept in the MP's flat. They broke the locks, collected everything in four suitcases and decamped with the booty. They had even hired an autorickshaw to take the stolen goods," Patna Senior Superintendent of Police Manu Maharaj said.
Police were today alerted about a person moving with four suitcases from Gandhi Maidan area to Sultanganj under suspicious circumstances, he said.
The accused, who was trying to flee to Hajipur, was nabbed by police and all valuables believed to have been stolen from the MP's flat were recovered from him, Maharaj said, adding, based on his inputs the others were promptly nabbed.
Police calimed that the total recovery comprising the valuables and the cash is around Rs two crore.