Investigators also found bits of duct tape in the grass outside the garage with a substance that appeared to be blood on them, the sources said, although police were awaiting forensic test results.
All three men's hands, feet, and faces were duct-taped before they were thrown into the river, law enforcement sources said.
Narcotics officers also searched a trailer on the same block of 72d. The man who lived in the home searched by investigators was often seen using the property where the trailer sat, neighbors said.
Police also retrieved a dark blue Audi believed to be connected to the case, parked at 22d and Winter Streets, Thursday afternoon, according to law enforcement sources.
Sources say the surviving man, also originally from Vietnam, has been targeted in the past. He was also arrested on a drug charge in New York this month, according to a report in the Daily Courier-Observer of Messena, N.Y.In July, he told police that an acquaintance had scratched his car, then told him to meet him in Chinatown, adding that he had a gun, according to a police report.
Earlier this month, he told police that two men pulled him from his car, beat him with a hammer, and told him to "get in their car before they kill him," according to a police report. Two men were arrested in the incident.
Two days after that incident, the man was arrested by border patrol agents near the Canadian border in New York with 85 bags of marijuana - weighing 51.5 pounds in total - stuffed into a black duffel bag in the trunk of a rented SUV, according to The Daily Courier-Observer.
The man and two others from Philadelphia were charged with drug possession and released the same day after paying a combined $17,500 in bail, according to the report.Investigators have not said whether these incidents are related to the man's abduction.
On Wednesday, the man, bloody from stab wounds and wearing only his underwear, flagged down police around 4 a.m. on Kelly Drive. He pointed police toward the two men chained to buckets in the shallows.
Police declined to identify the men. Department spokesman Lt. John Stanford said investigators were still waiting for autopsy results and trying to reach some of the men's relatives.
Police determined that a Vietnamese gang had given the brothers the $100,000 to buy drugs, according to law enforcement sources. Instead, they gambled the money away at Harrah's in Chester, law enforcement sources said. Members of the gang abducted them in retaliation, the sources said, and allowed one to call a friend - the 23-year-old - for money to repay their debt.
Police believe the 23-year-old showed up at the Southwest Philadelphia house where the men were held with $40,000, sources said. But he too was robbed, beaten, bound with duct tape, and stabbed, sources said.
The brothers' throats were cut before they were thrown into the Schuylkill, and they were weighted down with plastic buckets filled with tar, sources said. The third man was not weighted down, played dead, and was able to crawl out of the river once his captors left, sources said.
Anyone with any information on the incident is being asked to call the Homicide Unit at 215-686-3334.