It was just before 6 p.m. and still daylight on June 27, 2009, when police descended on the Piazza at Schmidts in Northern Liberties.

The newly opened apartment and shopping complex was teeming with people enjoying cocktails at the courtyard restaurants. Upstairs, on the top floor of the seven-story Navona building on North Hancock Street, residents had just discovered the bodies of a man and a woman, riddled with bullets, in the hallway.

Initially, police were unsure what the victims - 34-year-old Rian Thal, a party promoter well-known in the city's nightclub scene, and Timothy Gilmore, a 41-year-old long-haul trucker from Ohio - had to do with each other. Then they discovered a stockpile of cocaine and cash in Thal's apartment, and video surveillance of three gunmen ambushing the victims.

"Right away we knew we had several people involved, people who had shown they were dangerous to anybody," said Philadelphia Police Lt. Philip Riehl, the detective who supervised an investigation that lasted more than a year. "What if somebody had walked out into the hall while this was going on? It was pretty clear this was a no-witnesses-left-behind type of case."

The investigation expanded, stretching from a trucking business in Ohio to a Mexican drug cartel. Detectives spent weeks reviewing hundreds of hours of surveillance footage and reams of phone records, and knocking on doors of brothers, mothers, and girlfriends.

As with many murder investigations, a crucial break came in the first few days: A key witness surfaced and helped investigators uncover an elaborate plot that led to the arrests of eight people.

Four are serving life sentences after a trial that ended this month. Three others face years behind bars, and a final defendant is awaiting trial.

Solving the Piazza shootings was about stopping the killers from striking again, Riehl said. Seven of the defendants had arrest records, some for violent crimes. Five were on parole or probation.

"I never make a case about the victim," said Riehl, a 26-year veteran. "It's about the next victim. And if you do your job well, you can prevent the next victim."

Thal and Gilmore were two of 294 people killed in Philadelphia in 2009. Homicide detectives were already working 16 cases the day they were called to the Piazza.

Police say each investigation is pursued with the same level of manpower. For the first 48 hours after a murder, getting leads can call for around-the-clock work from at least a dozen officers.

The first officers on the scene found Thal outside her apartment door, shot execution-style in the back of the neck and the head. Gilmore was near the elevators, shot in the neck, arm, hip, leg, chest and hand.

Members of the homicide squad arrived and closed off the building to secure the scene, checking for fingerprints or other evidence. An officer began reviewing footage from the building's surveillance cameras.

In Thal's spacious living room, which looked out onto a balcony, investigators found a duffel bag containing clothes and men's shoes, said Detective Jack Cummings, as well as $4,000 in cash.

In Thal's walk-in bedroom closet, Cummings found a black trash bag containing a taped-up cigar box packed with money, plus bundle after bundle of cash, totaling more than $110,000. Nearby, Cummings found four kilograms of cocaine - more than eight pounds - wrapped in clear plastic and duct tape.

"That's when things started fitting into place," he said.

In the surveillance footage, Thal and Gilmore got off the elevator around 5:30 p.m. As they walked to her apartment, gunmen who were later identified as Edward Daniels and Antonio Wright came out of the stairwell and followed them. Donnell Murchison waited at the other end of the hall.

Thal and Gilmore were cornered, and Daniels put a gun to Thal's head. But Gilmore grabbed for Wright's gun and in a matter of seconds, gunfire erupted.

A camera captured Gilmore hurtling toward the elevators, falling to the floor as he was shot in the leg. The three gunmen ran past him, with Murchison shooting Gilmore point-blank on his way to the stairs.

The footage showed that the men had staked out the building for hours, and that Murchison had entered the keypad-secure lobby when he walked in after a resident.

The resident was Katoya Jones, who lived on the second floor. Police brought her to the station, but she denied any knowledge of the shootings. Some detectives believed her, Riehl said, and some didn't. But they had no cause to hold her, so she went home.

As detectives reviewed surveillance from earlier that day, they saw that Jones had lied. Cameras outside the building caught Jones waiting for Murchison and letting him in more than once, said Detective James Dunlap, who examined hours of footage.

Cameras were also rolling in the early hours of June 27, when Jones came to the lobby to let two other men in. Later identified as Will "Pooh" Hook and Robert Keith, the men were then filmed breaking into an empty apartment on the floor below Thal's.

Police brought Jones back to Police Headquarters on June 30. This time, investigators confronted her with the footage and showed her pictures of Thal's corpse.

"That's when she cracked," Riehl said. "That was the first big piece of the puzzle."

Jones said she had known Hook, a man police described as a drug dealer, for 10 years. He asked Jones to get him into the building June 27 so he could steal drugs and money from Thal. Jones expected to be paid for her help, and said she never thought anyone would get hurt.

Three days into the investigation, detectives had a motive and several suspects. But Jones could identify only Hook, who was not on the scene for the murders. She knew none of the gunmen.

Also unknown was the identity of a man captured on camera exiting Thal's apartment moments after the shootings. Police suspected he was linked to Gilmore, whose tractor-trailer truck was parked near the Piazza.

Gilmore's trucking log showed that he had driven from Texas, and a background check revealed that he ran a side business shipping drugs. With help from federal authorities, they learned Gilmore and the man, fellow trucker Edward Emerson, had connections to a Mexican drug cartel.

Emerson, a convicted robber and drug dealer, was already under investigation by the U.S. Drug Enforcement Administration. Gilmore and Emerson were on the East Coast to deliver cocaine, Riehl said, and arrived at the Piazza a few days before the murders.

"We start to see this case is about drug traffickers, drug suppliers, and the parasites trying to take them down," Riehl said.

Jones also had told police that Hook drove a white Dodge Challenger. On July 2, police pulled over 20-year-old Will Hook Jr. driving the car. Hook's son identified one of the gunmen in the Piazza video as his father's friend, Edward "Duck" Daniels.

Detective Ron Dove organized the numbers from Hook's call logs sequentially, allowing police to see who Hook talked to most in the days and hours before the shootings. One by one, police tracked down the people behind the numbers: Hook's girlfriend, his mother, Daniels, and others.

"For the next month, besides working on other cases, that's what we did," Riehl said.

Hook began emerging as the mastermind, with his phone showing dozens of calls with a posse of men even in the minutes before the shootings. As police identified Hook's associates, they matched his calls to the recipients by watching who talked on the phone in the surveillance footage. It became clear that Hook was calling the shots, Dove said.

"He was communicating with them constantly," he said.

From a desk in the lobby, detectives recovered a palm print left by Murchison when he was shown on camera leaning on it. Fingerprints in Jones' apartment led police to Keith, who broke into the empty apartment with Hook.

Keith was already in custody, having surrendered to his parole officer after the shooting on an unrelated matter. He was charged with burglary July 9. He told police he and Hook tried to break into Thal's apartment, but went to the wrong floor. Hook believed Thal had $500,000 in drugs and money, Keith said.

Keith's statement gave police all they needed to get an arrest warrant for Hook.

By then, Daniels had heard the police were on to him. He went to his parole officer July 11 and became the first shooter charged in the killings.

Police began circling Hook, visiting his girlfriend and others. Hook surrendered on July 13, denying any involvement in the case.

Langdon Scott, seen in the Navona building with the gunmen on June 27, was arrested July 23 after police identified him from Hook's phone records. Scott cooperated with police immediately. He told Detectives James Pitts and Ohmarr Jenkins that Hook invited him to buy cocaine from Thal, and that a man named Caesar Holloway drove him to the Piazza.

He was met by Hook, who was in a white van, as well as Murchison, who said he planned to rob Thal. Scott initially went along with it, then got cold feet and backed out at the last minute.

Security cameras caught a distinctive white van circling the Piazza that day. Cellphone records placed Hook at the scene.

Wright was arrested July 29. That same day, U.S. marshals staked out a home in the Northeast after getting a tip that Murchison was there. Murchison climbed out a window and ran into Pennypack Park, and a deputy marshal was hit by a car during the chase, but Murchison was caught.

Holloway was taken into federal custody on unrelated gun charges a month after the Piazza shootings. He was charged in the case in October 2010 and is awaiting trial.

In November 2010, Jones pleaded guilty to third-degree murder. She will be sentenced in January.

On Nov. 7, days before the trial in Common Pleas Court, Scott pleaded guilty to robbery, burglary and conspiracy. Hours later Murchison pleaded guilty to first-degree murder, taking a life sentence to avoid the death penalty. Keith pleaded guilty the next day.

Hook, Daniels, and Wright were convicted of murder Dec. 1. They were sentenced to life in prison.

Noting others who were instrumental in moving the case forward, Riehl cited Detectives Henry Glenn, Gregory Santamala, and George Pirrone, and Officers Victor Davila and Billy Golphin, numerous members of federal agencies, and the attorneys who prosecuted the case.

"It was such good police work all the way around," Riehl said. "Just think about how many bad people we got off the street in a short period of time. But you can't do that without having really good people on your team."

Contact staff writer Allison Steele at 215-854-2641 or asteele@phillynews.com.