The Central Bureau of Investigation (CBI) action came a week after it registered a case against criminal-turned-politician and former Samajwadi Party MP Ateeq Ahmed and 15 others.
A senior Central Bureau of Investigation (CBI) official told : "A team of officials today (Friday) questioned several officials posted at Deoria jail."
He said that the agency officials questioned the jail authorities over how the Lucknow-based real estate dealer Mohit Jaiswal was brought inside the jail premises by Ahmed's men.
The agency official said without the connivance of the jail authorities, no insider would have entered the jail premises.
He said that the entry of the kidnapped businessman along with Umar Ahmed, son of the former MP and his associates inside the jail premises and the assault, exposes the nexus between the jail authorities and gangsters.
This is not the first time that the nexus between the gangsters and the jail authorities have come to the fore in Uttar Pradesh.
Jaiswal was kidnapped on December 26 last year from Lucknow and taken to the Deoria prison.
The Uttar Pradesh Police has suspended five jail officials in connection with the case including the Jail Superintendent.
Last week, the CBI registered a case against Ahmed and others allegedly for kidnapping and assaulting Jaiswal and charged them under the sections of kidnapping, extortion, criminal intimidation, criminal conspiracy, cheating, forgery and robbery.
Ahmed was a Samajwadi Party MP in the 14th Lok Sabha representing Phulpur in Uttar Pradesh from 2004 to 2009. He was a five-time MLA and has been in jail since February 11, 2017.
In the past, Ahmed was associated with political parties including Samajwadi Party and Apna Dal (Sonewal faction).
The CBI has registered the case on the Supreme Court order of April 23, 2019.
The official said that they are planning to grill Ahmed, who is currently lodged in a Gujarat jail.
( With inputs from IANS )