The murder of a 45-year-old assistant professor of a Delhi University college at a high-rise society in Vasundhara Enclave took place within a five-and-a-half-hour window between Wednesday afternoon and evening, the police have ascertained, adding that they have identified 13 potential suspects, besides her estranged husband.Police said two masked persons, including a woman, were also seen entering the society on Wednesday, and are among the prime suspects. (ANI/ Representative)Further, only one person was involved in the incident, and the suspect was acquainted with the victim, as there was no sign of forced entry, officers aware of the investigation said on Friday.Police said two masked persons, including a woman, were also seen entering the society on Wednesday, and are among the prime suspects.An officer familiar with the probe, who requested anonymity, said the professor's last phone call was to her mother around 12.30pm on Wednesday. Around 6pm, the society handyman arrived at her flat to repair a window, but he found the gate locked from the outside and returned. “Since the flat remained locked from the outside until the locks were broken around 3pm on Thursday, it can be said with certainty that the woman was murdered within a span of five-and-a-half hours on Wednesday,” said the officer.The woman’s body was found with multiple injuries and cuts to her wrists in her sixth-floor flat when her sister arrived.Investigators said the forensics team found only one set of unidentified fingerprints inside the flat. They said the list of 13 suspects includes a woman, a 10-year-old boy and a man, who were seen entering the A Block of the society together and leaving the premises around 20 minutes later.The woman’s estranged husband, who lives in Bengaluru and has been locked in a divorce litigation for four years, has been summoned, two senior officers associated with the probe said.DCP (east) Rajiv Kumar said the victim’s sister called the police at 2.35pm on Thursday.The victim’s sister, who is 49 years old and lives in an apartment in the vicinity, said, “My sister’s driver, Sanjay, reached the society around 9.30am to pick her up. When she did not respond to his repeated calls, he went upstairs and found her flat locked from the outside. He waited for half an hour and then telephonically informed me.”DCP Kumar said the cameras installed at the entrance to the A Block and in the elevator were defunct. Besides a metal grille, the wooden door behind it was also locked from the outside.“Nothing was found stolen from the house. The way she was attacked with a blunt object indicates that she was killed in a rage or personal enmity and not for robbery. Our three teams are trying to locate the 13 people and interrogate them about their visit,” DCP Kumar said.