Two youths, who said they witnessed the collapse of constable Subhash Chand Tomar during a protest in the Capital, were called for questioning by the crime branch of Delhi police on Thursday.
Constable Tomar collapsed during the anti-rape protest at India Gate on Sunday and died of cardiac arrest early on Tuesday. Police said he was trampled upon by the crowd.
Eyewitnesses Yogendra Tomar and Pauline, however, told the media on Wednesday that the policeman collapsed while chasing the crowd and that he was not beaten or trampled by the protesters.
"We have called them today (Thursday)," deputy commissioner of police (Crime Branch) SBS Tyagi told IANS.
The crime branch was handed the case on Tuesday. The two will be questioned at the Chanakyapuri headquarters of the crime branch.
The eyewitnesses have challenged Delhi police's version of the constable being beaten by the crowd.
"He wasn't assaulted or trampled," Yogendra had said Wednesday. "He fell on his own while chasing the crowd. In fact, many protesters came to help him."
Pauline backed Yogendra's version and explained in detail how their efforts to revive the unconscious policeman failed.
She said she saw "no visible injuries" on the constable.
The police are also collecting video footage from news channels to establish the sequence of events.
TS Sidhu, medical superintendent at the Ram Manohar Lohia Hospital, where Tomar died, had also said on Wednesday that the constable had "no major external injury marks except for some cuts on his right knee and bruises on his chest" and "was brought here in a total collapsed stage".
Police on Wednesday quoted the post-mortem report, saying the constable suffered "multiple internal injuries produced with the impact of a blunt object on his neck and chest", though they did not talk about a mob attack.