Six persons were detained and pilgrims of Bangladeshi origin were among those questioned by security agencies in connection with the bomb blast at the sufi shrine of Khwaja Moinuddin Chisti in Ajmer.
As Union Home Secretary Madhukar Gupta the terrorist hand in the blast was "quite visible", Bangladeshi militant group Harkat-ul Jihadi Islami and its Karachi-based operative Shaid Bilal emerged as prime suspect behind the incident.
Some suspects are being interrogated since Thursday night but no arrests have been made in the blast, which claimed two lives, and left 17 injured, a senior official said.
"Police and intelligence agencies are interrogating suspected people who include pilgrims of Bangladesh origin and forensic experts are examining the nature of explosives used in the explosion", Additional Director-General of Police (Law & Order) Kanihya Lal said.
However, sources in Delhi said the interrogation of the six detained is unlikely to provide a breakthrough.
As security agencies and forensic experts examined the blast site, a crude bomb kept in a bag was found near the main gate of the shrine.
The bomb, which appeared to be similar to the one, which had gone off in the dargah complex on Thursday evening, was possibly to explode with an alarm of a mobile phone after the first blast.
The bomb was defused, Additional Director General of Police (crime) A K Jain said. A team of National Security Guards also examined the blast site.