Topline: A jury found Lisa Gonzales guilty of second-degree murder for killing Margaret Mamer and hiding her remains in a storage container.
Published: April 5, 2026 6:00 am ET
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Lisa Gonzales (via Bay City News)
SAN FRANCISCO, CA — A jury convicted 55-year-old Lisa Gonzales of second-degree murder for the 2018 killing and dismemberment of her roommate, Margaret Mamer, in their Mission District flat.
The jury also found that Gonzales personally used a knife during the commission of the crime, as reported by ABC 7. The verdict follows a trial that took place nearly eight years after the initial investigation began.
District Attorney Brooke Jenkins, who previously worked on the case in the homicide unit, said the verdict provides long delayed justice for a grisly crime.
“This is one of the most gruesome crimes our city has experienced in recent history,” Jenkins said. “I remember putting in the grand jury proceedings and having to call the witnesses to the stand to testify about what they heard and what they saw. And this was very gruesome. It was very difficult to get through that testimony.”
Mamer was reported missing June 1, 2018. Friends of the victim told authorities they were concerned because they had not heard from her and knew of growing tensions between Mamer and Gonzales.
On June 2, 2018, another individual informed police that a murder may have taken place inside the apartment on the 200 block of 14th Street. When officers arrived at the residence, Gonzales invited them inside and claimed Mamer had moved to Eureka several weeks prior.
During a search of the building storage area, investigators discovered a blue plastic container. The bin held human remains that were later identified as Mamer.
A third roommate provided testimony during the trial regarding the days following the disappearance. The witness told investigators she heard sawing noises coming from the bathroom for several hours.
The witness also reported smelling vinegar and bleach throughout the home. She testified to seeing a hacksaw under the sink and noticing that her own blue storage container was missing from the residence.
According to the District Attorney’s office, when the roommate asked where Mamer had gone, Gonzales said Mamer had left “but not in the way she wanted to.”
Coworkers of Gonzales testified that the defendant had complained for weeks about wanting Mamer to vacate the apartment. When coworkers suggested legal eviction methods, Gonzales reportedly declined and said she would handle the situation her way.
An autopsy performed on the remains determined that Mamer died from multiple sharp-force injuries to her head, face, skull and chest, according to reports from Mission Local.
Prosecutors argued that Gonzales dismembered the body to conceal the killing. The remains stayed in the storage unit for weeks before police found them. Jenkins said the delay in discovery resulted in decay of the body.
The passage of time between the 2018 arrest and the trial created challenges for the prosecution. Jenkins said delays often benefit the defense because witness memories fade and contact with individuals involved in the case can be lost.
Prosecutors initially sought a first-degree murder conviction. Jenkins said proving premeditation was difficult because Mamer, the only other person involved in the dispute, could not testify.
Gonzales remains in custody following the conviction. She faces a sentence of 16 years to life in prison. A hearing is scheduled for later this month to set a formal sentencing date.
Presumption of Innocence: A presumption of innocence means that any defendant in a criminal trial is presumed to be innocent until they have been proven guilty beyond a reasonable doubt in a court of law. The defendant in this case is only accused of the charges set forth in the criminal complaint. They are innocent until proven guilty.
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San Francisco Woman Convicted of 2018 Killing, Dismembering of Roommate
A jury found Lisa Gonzales guilty of second-degree murder for killing Margaret Mamer and hiding her remains in a storage container.
By Kate Byrd
Published: April 5, 2026 6:00 am ET
Lisa Gonzales (via Bay City News)
SAN FRANCISCO, CA — A jury convicted 55-year-old Lisa Gonzales of second-degree murder for the 2018 killing and dismemberment of her roommate, Margaret Mamer, in their Mission District flat.
The jury also found that Gonzales personally used a knife during the commission of the crime, as reported by ABC 7. The verdict follows a trial that took place nearly eight years after the initial investigation began.
District Attorney Brooke Jenkins, who previously worked on the case in the homicide unit, said the verdict provides long delayed justice for a grisly crime.
“This is one of the most gruesome crimes our city has experienced in recent history,” Jenkins said. “I remember putting in the grand jury proceedings and having to call the witnesses to the stand to testify about what they heard and what they saw. And this was very gruesome. It was very difficult to get through that testimony.”
Mamer was reported missing June 1, 2018. Friends of the victim told authorities they were concerned because they had not heard from her and knew of growing tensions between Mamer and Gonzales.
On June 2, 2018, another individual informed police that a murder may have taken place inside the apartment on the 200 block of 14th Street. When officers arrived at the residence, Gonzales invited them inside and claimed Mamer had moved to Eureka several weeks prior.
During a search of the building storage area, investigators discovered a blue plastic container. The bin held human remains that were later identified as Mamer.
A third roommate provided testimony during the trial regarding the days following the disappearance. The witness told investigators she heard sawing noises coming from the bathroom for several hours.
The witness also reported smelling vinegar and bleach throughout the home. She testified to seeing a hacksaw under the sink and noticing that her own blue storage container was missing from the residence.
According to the District Attorney’s office, when the roommate asked where Mamer had gone, Gonzales said Mamer had left “but not in the way she wanted to.”
Coworkers of Gonzales testified that the defendant had complained for weeks about wanting Mamer to vacate the apartment. When coworkers suggested legal eviction methods, Gonzales reportedly declined and said she would handle the situation her way.
An autopsy performed on the remains determined that Mamer died from multiple sharp-force injuries to her head, face, skull and chest, according to reports from Mission Local.
Prosecutors argued that Gonzales dismembered the body to conceal the killing. The remains stayed in the storage unit for weeks before police found them. Jenkins said the delay in discovery resulted in decay of the body.
The passage of time between the 2018 arrest and the trial created challenges for the prosecution. Jenkins said delays often benefit the defense because witness memories fade and contact with individuals involved in the case can be lost.
Prosecutors initially sought a first-degree murder conviction. Jenkins said proving premeditation was difficult because Mamer, the only other person involved in the dispute, could not testify.
Gonzales remains in custody following the conviction. She faces a sentence of 16 years to life in prison. A hearing is scheduled for later this month to set a formal sentencing date.
Presumption of Innocence: A presumption of innocence means that any defendant in a criminal trial is presumed to be innocent until they have been proven guilty beyond a reasonable doubt in a court of law. The defendant in this case is only accused of the charges set forth in the criminal complaint. They are innocent until proven guilty.
Editor's Note: ThePo makes every effort to accurately transcribe the contents of affidavits of probable cause contained in criminal complaints. Often, the complaints themselves are copies of copies of faxed copies, and are difficult to read. To confirm the accuracy of our transcription, contact the Magisterial District Court listed above and request a copy of the criminal complaint. It's a public record to which you are entitled.
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Editor Picks
Latest Articles
San Francisco Woman Convicted of 2018 Killing, Dismembering of Roommate
A jury found Lisa Gonzales guilty of second-degree murder for killing Margaret Mamer and hiding her remains in a storage container.
By Kate Byrd
Published: April 5, 2026 6:00 am ET
Lisa Gonzales (via Bay City News)
SAN FRANCISCO, CA — A jury convicted 55-year-old Lisa Gonzales of second-degree murder for the 2018 killing and dismemberment of her roommate, Margaret Mamer, in their Mission District flat.
The jury also found that Gonzales personally used a knife during the commission of the crime, as reported by ABC 7. The verdict follows a trial that took place nearly eight years after the initial investigation began.
District Attorney Brooke Jenkins, who previously worked on the case in the homicide unit, said the verdict provides long delayed justice for a grisly crime.
“This is one of the most gruesome crimes our city has experienced in recent history,” Jenkins said. “I remember putting in the grand jury proceedings and having to call the witnesses to the stand to testify about what they heard and what they saw. And this was very gruesome. It was very difficult to get through that testimony.”
Mamer was reported missing June 1, 2018. Friends of the victim told authorities they were concerned because they had not heard from her and knew of growing tensions between Mamer and Gonzales.
On June 2, 2018, another individual informed police that a murder may have taken place inside the apartment on the 200 block of 14th Street. When officers arrived at the residence, Gonzales invited them inside and claimed Mamer had moved to Eureka several weeks prior.
During a search of the building storage area, investigators discovered a blue plastic container. The bin held human remains that were later identified as Mamer.
A third roommate provided testimony during the trial regarding the days following the disappearance. The witness told investigators she heard sawing noises coming from the bathroom for several hours.
The witness also reported smelling vinegar and bleach throughout the home. She testified to seeing a hacksaw under the sink and noticing that her own blue storage container was missing from the residence.
According to the District Attorney’s office, when the roommate asked where Mamer had gone, Gonzales said Mamer had left “but not in the way she wanted to.”
Coworkers of Gonzales testified that the defendant had complained for weeks about wanting Mamer to vacate the apartment. When coworkers suggested legal eviction methods, Gonzales reportedly declined and said she would handle the situation her way.
An autopsy performed on the remains determined that Mamer died from multiple sharp-force injuries to her head, face, skull and chest, according to reports from Mission Local.
Prosecutors argued that Gonzales dismembered the body to conceal the killing. The remains stayed in the storage unit for weeks before police found them. Jenkins said the delay in discovery resulted in decay of the body.
The passage of time between the 2018 arrest and the trial created challenges for the prosecution. Jenkins said delays often benefit the defense because witness memories fade and contact with individuals involved in the case can be lost.
Prosecutors initially sought a first-degree murder conviction. Jenkins said proving premeditation was difficult because Mamer, the only other person involved in the dispute, could not testify.
Gonzales remains in custody following the conviction. She faces a sentence of 16 years to life in prison. A hearing is scheduled for later this month to set a formal sentencing date.
Presumption of Innocence: A presumption of innocence means that any defendant in a criminal trial is presumed to be innocent until they have been proven guilty beyond a reasonable doubt in a court of law. The defendant in this case is only accused of the charges set forth in the criminal complaint. They are innocent until proven guilty.
Editor's Note: ThePo makes every effort to accurately transcribe the contents of affidavits of probable cause contained in criminal complaints. Often, the complaints themselves are copies of copies of faxed copies, and are difficult to read. To confirm the accuracy of our transcription, contact the Magisterial District Court listed above and request a copy of the criminal complaint. It's a public record to which you are entitled.
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