Hundreds of mourners gathered Saturday at the suburban Chicago church that Sandra Bland attended for many of her 28 years, turning out in such numbers that even the overflow viewing room ran out of chairs. From the pulpit, relatives and friends recounted happy memories of Ms. Bland’s faith and social activism, and restated their belief that her death in a Texas jail was no suicide.
“That baby did not take herself out of here,” said Geneva Reed-Veal, Ms. Bland’s mother, during the funeral here at DuPage African Methodist Episcopal Church.
Ms. Reed-Veal spoke at length, telling mourners about a recent road trip she had taken with her daughter. On their way to visit relatives in Tennessee, Ms. Reed-Veal said, Ms. Bland told her she had found a calling and planned to pursue it by returning to Texas, where she had attended college.
“Her purpose was to stop all injustice against blacks in the South,” Ms. Reed-Veal said at the funeral.
Many here believe that in seeking to fulfill that newfound purpose, Ms. Bland became another victim of the injustice she wanted to end. Shortly after arriving in Hempstead, Tex., where she had moved to take a job at Prairie View A&M University, the historically black school that was her alma mater, she was pulled over by a state trooper.
What started as a traffic stop escalated to an arrest and a charge of assaulting a public servant. On July 13, three days after she was arrested and jailed, Ms. Bland was found hanged in a cell at the Waller County Jail. A county prosecutor in Texas said Thursday that an autopsy had concluded that Ms. Bland’s injuries were consistent with suicide. The authorities have said she used a trash can liner to hang herself, a conclusion that many people here dispute.
Leaders at DuPage remembered Ms. Bland as a smart, outspoken woman who once sang in the youth choir and had participated in the church’s Girl Scout troop. After graduating from college, she returned here, serving on church committees, befriending older members of the congregation and earning a reputation as a prolific taker of selfie photos.
The Rev. Theresa Dear, an associate minister at DuPage A.M.E. who knew Ms. Bland since she started attending the church as a young girl, said the official account of the death conflicted with her own memories of an ambitious, educated Christian who was excited about the future and who had helped organize the church’s recent Women’s Day event.
“This is someone who had over 50 selfies, healthy self-esteem,” Ms. Dear said in an interview. “Someone who had two job offers. Someone who just talked to her family and knew that help and rescue was on the way. This is someone who knew the Lord and was extremely close with her church family and her sisters, her biological family.
“None of that adds up to taking one’s life or suicide.”
Saturday’s funeral was mostly a celebration of Ms. Bland’s life: her commitment to her sorority, Sigma Gamma Rho; her involvement at church; her skills on the trombone; her college degree in agricultural food sciences; and her recent social media posts critiquing race relations in America.
“We’re not funeralizing a martyr or a victim,” said the Rev. James F. Miller, who officiated. “We’re celebrating a hero.”
But the circumstances around her death were discussed openly and repeatedly, and Mr. Miller had harsh words for the Texas officials handling the investigation.
“The authorities in Waller County are going to discover something that I learned and each of us learned at our mother’s knee,” Mr. Miller said from the pulpit. “You can disrespect a strong black woman if you want, but you’re going to pay for that.”
Speaker after speaker encouraged mourners to continue to use social media to seek justice. Twitter hashtags used by activists were printed in the funeral program and displayed by a handful of people on T-shirts. Ms. Reed-Veal also asked that supporters take cues from her and her lawyer on how the family wanted to proceed. She said protesters should not demonstrate outside the home of Brian T. Encinia, the trooper who arrested Ms. Bland.
“We want to do this the right way,” Ms. Reed-Veal said.
Senator Richard J. Durbin and Representative Bill Foster, both Democrats of Illinois, each spoke briefly at the funeral. They said they had asked the Justice Department to investigate Ms. Bland’s death.
Mr. Durbin said the circumstances started with a “highly questionable traffic violation.” Trooper Encinia, of the Texas Department of Public Safety, has said he pulled Ms. Bland over after seeing her change lanes without signaling. Mr. Durbin noted that he had seen plenty of people change lanes without a turn signal during his drive to the church on Saturday.
“It was an amazing life that was cut way, way too short,” Mr. Durbin told the congregation.
A video of Ms. Bland and Trooper Encinia, taken by the dashboard camera in the trooper’s car, shows the encounter turning into a disagreement over whether Ms. Bland had to extinguish a cigarette, then escalating to her being threatened with a stun gun, removed from her car and handcuffed as she lay sprawled on the ground.
She was taken to the jail and charged with assaulting Trooper Encinia, 30, who has been moved to a desk job for violating department policies during the stop.
Ms. Bland’s death spurred skepticism and outrage on Twitter, where her name became a trending hashtag invoked alongside tags for Michael Brown, the black 18-year-old killed last year by a police officer in Ferguson, Mo., and Freddie Gray, the black man who died this year after being arrested by the Baltimore police.
Members of DuPage A.M.E. held a march in Ms. Bland’s honor last weekend, and demonstrators in Texas have protested her death.
Ms. Bland herself had been active online in recent months, posting videos that called for improvements to race relations in America and questioned how police officers treat black people. She “found her voice in social media and the civil rights realm and space,” Ms. Dear said.
In one of those videos, Ms. Bland told viewers that she had depression and post-traumatic stress disorder, but had found solace in her faith. Cannon Lambert, a lawyer for the Bland family, has said relatives were not aware of any clinical diagnosis of depression or of any medication she was taking for that condition.
Texas officials have said Ms. Bland told her jailers that she had attempted suicide before. Sheriff R. Glenn Smith of Waller County said in an interview on Friday at the jail that he regretted that Ms. Bland had not been placed on a suicide watch. He said he was reviewing the chain of events that ended with the discovery of Ms. Bland’s body in her cell, adding that he was considering disciplinary action against staff members for failing to fulfill state mental health training requirements.
But on Saturday, even amid all the talk about Ms. Bland’s death, even as white flowers were tossed on her coffin as it was lowered into the earth, those who knew her made an effort to keep a focus on her life. This was the woman everyone here called Sandy, a gifted musician who grew up in the church, loved spicy foods and was just getting settled in her new home in Texas before the arrest.
“Sandy was ours,” Mr. Miller said at the funeral. “We take care of our own. We love her.”