Constable Subhash Chand Tomar, 47, had "no major external injury marks except for some cuts on his right knee and bruises on his chest", the head of the Ram Manohar Lohia Hospital here said.
"He was brought here in a total collapsed stage," Medical Superintendent T.S. Sidhu told the media.
"He had already suffered a cardiac arrest and had almost no pulse. We revived him and shifted him to the ICU and he was put on ventilator," he added.
Asked if there was any internal bleeding, Sidhu said: "The x-ray did not show internal bleeding."
But he added that he would make a final comment only after going through the post-mortem examination report.
Police had earlier asserted that Tomar was badly beaten up near India
Gate during street protests Sunday against the gang-rape of a 23-year-old woman who remains in critical condition.
Police also said that the constable, who joined Delhi Police in 1987, was injured in chest, neck and head and that protesters had kicked and punched him after he fell on the street.
The policeman was cremated Tuesday with state honours.
Yogendra, a young man who claimed he saw the policeman fall, said Tomar collapsed while chasing the protesters on a street leading to India Gate.
"He wasn't assaulted or trampled," Yogendra told television news channels. "He fell on his own while chasing the crowd. In fact many protesters came to help him."
Police arrested eight people Sunday night for the alleged attack on Tomar but were granted bail the next day.
On Tuesday, after Tomar died, police said the accused would be booked for murder.