McGinnis said investigators believed five robberies were "absolutely connected" after viewing surveillance video from the casino showing the same man watching the victims as they cashed out at the waterfront gaming hall.
Detectives suspect that after identifying targets, the spotter, who often appears in the videos with a cellphone to his ear, calls two accomplices, who follow the patrons in a car and then rob them when they arrive home.
The pattern emerged when the stickup men used a Taser on the victims of the latest robberies, including a pregnant woman, early Sunday and Tuesday, McGinnis said.
After determining that the victims had been to SugarHouse, investigators started reviewing casino surveillance video and checking other robberies in the city to see if the victims also had just returned home from a night of gambling.
"You can imagine the hours of video that had to be viewed," he said.
The three other connected robberies occurred Sept. 13, Aug. 30, and Aug. 15.
McGinnis said the amounts taken in the five stickups ranged from $3,000 to $18,500.
Police released video of the suspected spotter as well as of two cars used by team members. The spotter appears to drive a Chevrolet Monte Carlo, while the stickup men in at least one instance left in a Toyota Camry or Ford Focus, detectives said.
McGinnis said that in all five connected robberies, the victims were Asians who lived in different parts of the city.
Of the five additional robberies, four, also involving Asians, took place in the city. The fifth involved a non-Asian victim was in Lower Moreland Township.
Four of the victims, including the pregnant woman, required hospital treatment after the robberies.
McGinnis said investigators were looking at more stickups to see if they are connected, adding, "We don't know that they are only targeting Asians."
The number of Asian victims, however, underscored concerns about gambling in the Asian community.
"The downside of gambling is a big issue in the Asian community," said Nina Ahmad, chairwoman of Mayor Nutter's Commission on Asian American Affairs. "Along with this kind of industry comes crime. That's just the way it is."
"Are Asians being targeted because they happen to be the ones gambling and winning? Are they targeted because people think they are easy targets? What is SugarHouse doing in response? Have they heightened security, made the environment safer?" Ahmad said she planned to ask those questions Friday night at the Asian American commission's regular meeting.
SugarHouse security director Tony DiLacqua said, "Nothing is more important than the safety of our guests."
DiLacqua, a former Philadelphia police chief inspector who appeared with McGinnis at the news conference, said the casino was working closely with the Police Department.
Merlin Wahyudi-Lamson, a social worker of Indonesian and Chinese descent, works with Asian clients in South Philadelphia, many of them low-income factory workers, including illegal immigrants.
She estimated that 50 percent of her clients gamble regularly "to relieve stress" and for fun.
"Sometimes they do go to Atlantic City," she said, "but since SugarHouse is so close, now they go to SugarHouse."
She said she was unfamiliar with the SugarHouse-related robberies. But many of her clients, she said, have experienced street robberies and beatings - preyed upon, she suspects, because being undocumented, and therefore unable to open bank accounts, makes them vulnerable.
Anyone with information about the identity of the spotter or his accomplices is asked to call the tip line at 215-686-4877.
Contact Joseph Gambardello at 215-854-2153 or email@example.com,
Inquirer staff writer Michael Matza contributed to this article.