Hakiakat Pannag, 59, was shot in the head eight times. He was found with his head on a pillow in a bedroom.
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His wife, 62-year-old Parmjit Kaur, was shot four times in the head and once in the arm. She was found lying on the living room floor.
Their daughter, 39-year-old Shalinderjit Kaur, was also found on the living room floor. She'd been shot three times.
Parmjit's sister who had been visiting from India, 58-year-old Amarjit Kaur, was shot twice in the head and was also found in the living room.
Police found all four dead at the Wyndtree Drive apartment on April 28 after responding to a 911 call at about 9:50 p.m. At least one of the victims had been preparing food, which was burning on the stove by the time police arrived. Investigators believe the victims were killed at about 9:15 p.m.
PHOTOS: 4 bodies found in West Chester apartment, police investigating as homicides
The preliminary autopsy reports do not generally say at what range the shots were fired, except for Hakiakat, who was shot at "intermediate range."
Officials said they didn't know when the final autopsies would be complete.
Investigators have been mostly quiet about the case since they executed a search warrant related to the case at another West Chester apartment earlier this month. Court officials said the search warrant is sealed, and authorities haven't said what they were looking for.
While many details haven't been publicly shared, police have repeatedly assured members of the local Sikh community that the case is their "top priority." Jasminder Singh, the president of the local Guru Nanak society, said West Chester Police Chief Joel Herzog personally visited the Sikh temple to speak about their commitment to the case. Officials have said they do not believe the incident was a hate crime.
"The victims and their families are on our minds every step of the way in this investigation," Herzog previously said.