They were known in law enforcement circles as "suppliers to the suppliers," father-and-son narcotics traffickers who sold cocaine in bulk to big-time drug dealers in Philadelphia and its suburbs.

In the spring, Ricardo McKendrick, 56, and Ricardo Jr., 36, were arrested in one of the biggest drug raids in city history.

On April 2, authorities found 274 kilograms of cocaine - more than 600 pounds - stashed in the elder McKendrick's South Philadelphia rowhouse. They also uncovered more than $1 million in cash, most of it in the trunk of a Mercedes-Benz parked in the garage of the younger McKendrick's house in Woodstown, N.J.

Authorities touted the bust as a major blow to the city's multimillion dollar narcotics trade.

"We are taking the city back" from drug dealers who bring "death and destruction to our streets," Mayor Nutter said the next day, at a news conference attended by Police Commissioner Charles H. Ramsey and then-U.S. Attorney Patrick L. Meehan.

Last month, with little fanfare and no media attention, the McKendricks entered guilty pleas in the case.

Potentially more significant, it appears that at least one of them could be cooperating with law enforcement - a development that could lead to several other cases.

"They know everybody," said a detective who asked not to be identified because of his role in continuing investigations. "It would be a major break."

If either McKendrick has flipped, investigators will have access to inside information about the movers and shakers who populate Philadelphia's highly secretive and violent drug underworld.

"It could be monumental," said Sean Patrick Griffin, a professor at Pennsylvania State University and former Philadelphia police officer who has written two books on black organized crime in the city.

"They know the landscape. They've known it for decades," said Griffin, whose book Black Brothers Inc. places the elder McKendrick in the hierarchy of the Philadelphia Black Mafia in the 1970s.

He was a "narcotics entrepreneur, a businessman-drug dealer," Griffin said.

Authorities have described the McKendricks as expediters, highly compensated brokers who bought from out-of-town suppliers in bulk and sold to local distributors who funneled drugs to neighborhood dealers and street-level traffickers.

"The sheer amount of drugs and money involved in this case is truly staggering," a federal prosecutor wrote in a pretrial document that described the McKendricks as part of a "large-scale drug-distribution ring."

Father and son are scheduled to be sentenced by U.S. District Court Judge Gene E.K. Pratter in March. They have been held without bail since their arrests.

The elder McKendrick has pleaded guilty to a drug-conspiracy charge. He faces 10 years under terms of a plea agreement filed in federal court on Dec. 10. Originally he was looking at mandatory life.

McKendrick Jr. - known as Li'l Rick - entered a guilty plea on Dec. 3, but documents relating to his plea agreement are filed under seal and unavailable for public examination.

Though it is not the only reason, records often are sealed in cases involving individuals who are cooperating with authorities. The move is intended to protect them from retribution and to keep investigations that come from information they provide secret.

Contacted last week, Assistant U.S. Attorney Leo Tsao, the prosecutor in the case, declined to comment on McKendrick Jr.'s status and would not respond to questions about why parts of his court record had been sealed.

McKendrick Jr.'s lawyer, Brian McMonagle, said he could not talk about the case.

Arnold Joseph, who represents the elder McKendrick, said his client was not cooperating. Joseph called the potential 10-year sentence a fair deal, but would not comment on whether the father had benefited from any arrangement worked out by his son.

Ricardo McKendrick Sr. has a string of narcotics arrests dating to the 1970s. Among other things, sources say, he was a suspect in the murder of a Black Mafia member who was decapitated.

The younger McKendrick was jailed in 1995 on assault and weapons charges and served about a year in prison. He has no other arrests.

In a memo filed during a detention hearing in April, Tsao said the 274 kilograms of cocaine found in the elder McKendrick's rowhouse had a street value of roughly $28 million. It was "one of the biggest drug seizures in the history of the city," he said.

"The sheer quantity of the drugs involved in this case confirms that the defendant is a major drug supplier," Tsao wrote in separate memos seeking to bar each defendant from obtaining bail.

Authorities have been tight-lipped about the case ever since.

The McKendricks were arrested after being targeted by the FBI and the Philadelphia Police Department's Narcotics Bureau.

Tipped by an informant that a major shipment of cocaine was due at the elder McKendrick's rowhouse at 2606 Federal St. in the city's Grays Ferry section, investigators set up surveillance.

After observing McKendrick Jr. engage in what appeared to be two drug transactions at the home on the night of April 1, they moved in, according to an affidavit submitted by Detective Andrew J. Callaghan, an investigator with the FBI's Violent Gang and Drug Task Force, which worked the case.

According to the affidavit, McKendrick Jr. was followed as he drove away and was stopped after briefly trying to elude police. Investigators found $54,971 in plastic bags in his Ford 500.

A police dog trained to sniff out narcotics had a positive reaction to the front doors and trunk of the car, the document states.

Police then obtained a search warrant for the house on Federal Street. At 1:15 a.m., as the elder McKendrick walked toward his door, authorities closed in.

In addition to the cocaine, police found a loaded .38 caliber handgun, $6,028 in cash, packing materials, and a pressing machine used for making kilogram "bricks" of cocaine.

Most of the cocaine was stored in seven 55-gallon drums, police said. There were also several bricks.

Federal agents then obtained a search warrant for the Salem County house and Mercedes-Benz of the younger McKendrick. Authorities found $982,144 in duffle bags in the trunk of the car, which was parked in the garage of a two-story house on Rockwell Lane in Woodstown.

McKendrick lived there with his wife, Dawn Edge McKendrick, a lawyer with the U.S. Equal Opportunity Employment Commission in Philadelphia.

Investigators discovered an additional $9,243 in the house, which is in an upscale neighborhood around the corner from a golf course and just a few blocks from Woodstown High School.

McKendrick and his wife bought the property, valued at about $400,000, in 2002 shortly after it was built.

At the time of his arrest, McKendrick owned a newsstand at 54th Street and City Avenue, near St. Joseph's University, according to court documents. He held a license to operate a Pennsylvania State Lottery machine at the site.

"They were quiet, never said much," a Rockwell Lane neighbor said last week. Like others on the block, he asked not to be identified because of the nature of the case.

"They would wave and say hi, but they never socialized with anyone. No one ever knew what he did for a living," he said. "I guess now we know why."

Nutter, according to reports from the news conference when the McKendricks were charged, said the case underscored the deadly nature of their business.

"It's about drugs, it's about turf, it's about money," he said.

Contact staff writer George Anastasia at 856-779-3846 or ganastasia@phillynews.com.