In a letter to the paediatrician, who is now on bail, Mr Gandhi said the attack on his brother Kashif Jameel exemplified the law and order situation in Uttar Pradesh.
Mr Jameel was shot at in Gorakhpur on Sunday night and is now admitted at the King George Medical University trauma centre in Lucknow.
Mr Gandhi demanded a probe into the "laxity" in the case, Uttar Pradesh Congress spokesman Amarnath Agarwal said today.
Mr Agarwal said the Congress president has praised doctor Kafeel Khan for not compromising on his self-respect despite the hardships caused by the state government's "vindictive attitude".
Mr Gandhi's letter said the doctor's patience was a source of inspiration for the common people.
Doctor Kafeel Khan yesterday met UP's Additional Director General of Police (Law and Order) Anand Kumar and told him of the "laxity" of police officers in Gorakhpur.
Mr Jameel was shot at by three unidentified miscreants. Some reports suggested that the cause was a property dispute.
Three bullets hit Mr Jameel in the neck, chin and arm.
Doctor Kafeel Khan was arrested after several children died at Gorakhpur's BRD Hospital allegedly due to a shortage of oxygen cylinders.
His family had claimed that the doctor was being made a scapegoat in the case.
On his release on bail, Mr Khan offered to help out Kerala government to deal with an outbreak of the Nipah virus.
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