The attacker, identified as Kapil Thakur, in his 30s, is from Gwalior in Madhya Pradesh and is married with three children. He was visiting his mother and younger brother in east Delhi's Geeta Colony, police said.
"As he watched the news of Kalmadi being produced in Patiala House court complex, he could not hold back and reached the spot to attack him," said a police officer.
Kalmadi was walking towards the court complex when Thakur first tried to break the police cordon, and when he failed, chucked a slipper at Kalmadi.
"No case has been registered against him and he has been detained at the Tilak Marg police station (central Delhi) where he is being questioned. We cannot comment on when he would be released," the police official said.
Police are also investigating Thakur's claim of being a former lawyer in Gwalior, said the official.
Kalmadi was arrested Monday for alleged conspiracy to favour a private timing device firm in Switzerland for the October 2010 Commonwealth Games.
Published 26 April 2011, 14:19 IST