Investigators would not say who called police, but they said that Pappert was waiting for them when they arrived. He was later charged with murder and related offenses.
The only motive that police released for the killing was a domestic argument, though they declined to speculate on the nature of the fight.
The elder Pappert allegedly shot his daughter once in the right side and once in the left arm. She was transported to Temple University Hospital, where she was pronounced dead at 5:20 a.m., police said.
A neighbor, who asked not to be identified, said that Allyn Pappert and his daughter rarely came out of their home.
"He's a recluse, that guy, you never see him," the neighbor said. "The only time he came to the door is when the pizza guy came around."
The neighbor said that the house was in horrendous condition and that, for a time, the Papperts went without electricity.
"The house was falling apart," he said. "I doubt the police even wanted to go in there."
The first killing in the city on Valentine's Day yesterday occurred just hours earlier, about 2 a.m., on Germantown Avenue near Cumberland Street, in North Philadelphia.
Police said that a 24-year-old man, whose identity was not released pending family notification, was shot once in the chest inside of L's Comfort Zone following a fight.
The victim was able to crawl across Cumberland Street after being shot, but he was pronounced dead at 2:27 a.m. after being taken to Temple University Hospital, police said.
There were no suspects in the case as of last night.
This weekend's homicides began about 10 p.m. Friday when a man was shot to death on Trinity Street near 58th, in the city's Kingsessing section.
The 21-year-old man, whose identity has not been released pending family notification, had run into a store from a vehicle double-parked on Trinity Street and was coming out when he was approached by an unknown gunman, police said.
He hopped into the back seat of the vehicle, driven by his friend, but before they could get away, the gunman fired through the car's rear window, striking the man in the right side of his head.
The victim was taken to the Hospital of the University of Pennsylvania, where he was pronounced dead at 10:30 p.m.
And finally, shots rang out in front of the Local 19 Sheet Metal Workers Union hall, on Columbus Boulevard near Reed Street along the waterfront, injuring four people attending a party there Saturday night, according to police.
A fight spilled out from a party inside the union hall into the parking lot around 2 a.m. During the fight, a man described only as a light-complected black man, around 5-foot-10 with a thin build and glasses opened fire on the crowd, injuring four men, police said.
Two of the victims took off in a gray Mazda before crashing into a center median along Columbus Boulevard, where they were found by police.
Both men were transported to Thomas Jefferson University Hospital and listed in stable condition. One of the men, a 25-year-old, was treated for a gunshot wound to his wrist. The other, a 27-year-old man, suffered several shots to his right leg, police said.
Two men at the scene were transported by a private car to Pennsylvania Hospital. One, a 24-year-old who was shot once in his right forearm, was listed in stable condition while the other, a 27-year-old man who was shot in his lower abdomen, remained in critical condition last night, according to police.