Wade Michael Page is dead, killed by police after the shootings outside Milwaukee. Although detectives are pursuing leads in several states, their findings might never be presented in court.
So will the full story behind the attack ever be known? And how long will investigators keep looking for an elusive motive that might provide answers to devastated Sikh families, as well as valuable information about white supremacists?
At the moment, detectives are sifting through the gunman's life, assembling the biography of a man who apparently had few relatives, a spotty work history and a thin criminal record. The Sikh community holds out hope for answers.
Wade Michael Page is seen in this undated picture from a myspace.com web page for the musical group End Apathy. Reuters/myspace.com/Handout
"We just want to get to the bottom of what motivated him to do it," said Amardeep Singh, an executive with the New York-based Sikh Coalition.
"It's important to acknowledge why they lost their lives."
The 40-year-old Army veteran strode into the Sikh Temple of Wisconsin shortly before Sunday services and opened fire with a 9 mm pistol.
The dead included temple President Satwant Singh Kaleka, who was shot as he tried to fend off the shooter with a butter knife.
Page wounded a responding police officer in the parking lot before another officer killed Page in a shootout.
The FBI has taken over the case and released little official information. The fragments of Page's past that have emerged suggest he lived a somewhat troubled life.
The Southern Poverty Law Center has described Page as a "frustrated neo-Nazi" who participated in the white-power music scene, playing in bands called Definite Hate and End Apathy.
If detectives determine Page simply held a personal grudge, the Sikhs and the rest of the public will have an answer.
If investigators conclude he was motivated by racist ideology, that might lead police to accomplices, help collect intelligence on white supremacist groups and prevent future attacks.
Rajwant Singh, chairman of the Sikh Council on Religion and Education, said even though Page is dead, other white-supremacy and neo-Nazi groups could harbor similar intentions.
Amardeep Kaleka, son of the president of the Sikh Temple of Wisconsin comforts members of the temple in Oak Creek, Wisconsin. AP/M Spencer Green
"Our concern is, how do we tackle these hate groups operating underground or in darkness?" he said.
The FBI has classified the incident as domestic terrorism, a violent act for social or political gain. But the bureau hasn't said anything about Page's possible motives.
Now investigators face two tasks: determining what drove Page over the edge and whether anyone nudged him along the way.
The bureau's special agent in charge in Milwaukee, Teresa Carlson, said investigators have no information to suggest that anyone else was involved, but they continue to search to make sure.
A native of Littleton, Colorado, he had a record of minor alcohol-related crimes in Texas, Colorado and North Carolina.
He was demoted during a stint in the Army for getting drunk on duty and going AWOL before he was discharged in 1998.
Page eventually moved to Wisconsin, living in South Milwaukee with a girlfriend and working third-shift at a brazing factory in Cudahy, another Milwaukee suburb.
Neighbors said the couple broke up this past spring. Page moved into a Cudahy duplex in mid-July and quit showing up for work around the same time.
A few days after he moved into the duplex, he visited a gun shop and, after clearing background checks, bought the gun he used in the shooting.
Investigators probably will collect all the bullets and fragments from the temple and the victims' bodies to confirm that they came from Page's gun. Detectives also will pore over witness statements to make absolutely certain he was the only shooter, said Joe LeFevre, chairman of the forensic science department at Fox Valley Technical College in Appleton.
Authorities will interview Page's family, friends and associates. Agents spent Monday morning doing a door-to-door sweep on his street, chatting with neighbors on their front porches and in their backyards.
"It's like any crime," said Jack Ryan, a Rhode Island attorney who trains police around the country.
"You focus on their recent tracks. You focus on friends, acquaintances. He had to get ready for this plot somewhere."
The investigation could take weeks or longer.
Page's girlfriend, 31-year-old nursing student Misty Cook, faces legal trouble herself. She was arrested on a tentative charge of being a felon in possession of a firearm, South Milwaukee police said on Tuesday.
There was no immediate indication that her arrest was linked to Sunday's shooting, and police refused to release additional information.
Details of Cook's felony conviction weren't immediately clear.
The voicemail on Cook's cellphone was full and wouldn't accept a message.
However, in regard to the shooting, she told the Milwaukee Journal Sentinel in an email: "If I could say something to ease the pain of the victims and their families, I would gladly do so. Unfortunately, words do not begin to heal the pain they are going through."
Mass shooting incidents in last 20 years
Children who spotted shooter seen as heroes
Gurdwara head fought shooter with kirpan, turns into hero
Gurdwara shooting: FBI rules out involvement of second person
US flags to fly at half-staff till Aug 10 to honour Gurdwara shooting victims