Teams of Forensic Science Laboratory (FSL) scientists and Delhi Police Crime Branch visited the Markaz Nizamuddin here on Sunday to carry out an investigation in connection with a congregation held here in which thousands of people took part between March 13 and March 15.
An FIR was earlier filed against Tablighi Jamaat head Maulana Saad and others under the Epidemic Disease Act.
Around 2300 people were brought out from the Markaz on April 1.
Delhi Chief Minister Arvind Kejriwal had said that of the 2300 brought out from the Markaz, 500 showed the symptoms of COVID-19 and were admitted to hospitals, whereas the remaining 1800 were sent under quarantine.
The Tablighi Jamaat event has emerged as a hotspot for COVID-19 after several positive cases across India were linked to the gathering, including deaths in Maharashtra, Karnataka and Telangana.