Bishop Lester Williams, who was to officiate Bell's marriage and ended up presiding over his funeral, is overseeing a rally and memorial at the church.
Earlier Thursday, Laura Harper-Paultre, the woman who would have been Sean Bell's mother-in-law, briefly attended the vigil at the church.
She prayed for a guilty verdict and for peace in Queens following the decision.
Friday morning, those taking part in the vigil will march from the church to Queens Supreme Court, where Justice Arthur Cooperman will read his verdict.
Meanwhile, the New York Police Department is bracing for the decision. Officials have downplayed reports that 1,000 officers will be deployed outside the courthouse in Queens and near the spot where Sean Bell was killed hours before his wedding.
NYPD spokesman Paul Browne declined to specify any plans. The department, though "always ready for any eventuality," doesn't expect serious trouble, he said.
The mood has been tempered by several factors. Racial tensions in the city are low compared to the Amadou Diallo era, when then-Mayor Rudy Giuliani had poor relations with the black community. And in the Bell case, two of the officers are black, making it less racially charged.
Mayor Michael Bloomberg has said he believes calm will prevail after the verdict.
"My expectation is that no matter what the decision is, everybody will act in a dignified manner no matter what they think," the mayor said.
Bell, 23, and the two companions were shot on Nov. 25, 2006, after a bachelor party at a seedy strip club in Queens that police had targeted for an undercover vice operation.
The defense claims that undercover officer Gescard Isnora, who was posing as a club patron, believed a gunfight involving Bell and his friends was brewing when he confronted them as they entered Bell's car and identified himself as an officer. He and the other officers opened fire after Bell violently pulled away and crashed into an unmarked police van.
The prosecution has portrayed the defendants as trigger-happy cowboys who shot first and made up a reason for it later when they realized no gun was in the car. The surviving victims testified they were shocked when a stranger in street clothes - Isnora - confronted them and began shooting without warning.
The three detectives charged with manslaughter, assault and reckless endangerment opted to have a judge, state Supreme Court Justice Arthur Cooperman, decide their case instead of a jury.
If convicted, Isnora and Michael Oliver face up to 25 years in prison; Marc Cooper faces up to one year on the lesser endangerment count. If acquitted, the officers still could be hit with departmental charges and possible dismissal from the force, and the city still must contend with multimillion-dollar civil lawsuits brought by the families of the victims.
The slaying of Bell has drawn obvious comparisons to that of Diallo: Both victims were young black men gunned down while minding their own business - Diallo was on his doorstep reaching for his wallet when he was shot. In both cases, the victims were shot by officers who claimed their targets were acting suspiciously and that deadly force was necessary.
The onslaught of pretrial publicity in the Diallo case convinced an appeals court to move the trial of four officers to Albany, where a jury cleared them following a trial 2000. The news prompted protesters to take to the streets in Manhattan and elsewhere in New York, resulting in about 100 arrests.
The Rev. Herbert Daughtry, who helped orchestrate widespread civil disobedience over Diallo's killing, said protesters "were flocking in to get arrested" at the demonstrations.
After Bell's killing, there was a peaceful march involving several thousand people - many drawing comparisons to the Diallo case - as Sharpton rallied support for the victim's grieving fiancee and parents. Demonstrations after that were small, sporadic and uneventful.
When it comes to the Bell case and protests, "The stamina's not there," said Norman Siegel, a lawyer and longtime civil rights advocate.
Siegel theorized that police critics, disappointed that the Diallo case failed to result in meaningful reforms, have retreated because "they don't think the script is going to be any different."
Both Siegel and Daughtry said the mass anti-police protests in 1999 were fueled in part by the indifference of Bloomberg's combative, ceaselessly pro-law enforcement predecessor, Giuliani. By contrast, Bloomberg was quick to meet with black and religious leaders, afterward telling reporters, "It sounds like to me like excessive force was used." Daughtry said no matter how the case concludes, he'll focus on comforting Bell's family.
"When the marching feet stop marching, the cameras stop clicking, when all the shouting dies down, this family will still have to deal with the face that their young son is dead," he said.
