Parkland school shooter Nikolas Cruz is a sociopath who etched swastikas on his gun magazine and wrote online that "the Nazi party will rise again," witnesses testified Tuesday at his Florida trial.

The prosecution's rebuttal case began with Broward Sheriff's Office Sgt. Gloria Crespo, who displayed the rifle that Cruz used in the murderous rampage and left behind in a stairwell. 

There were swastikas etched on either side of the magazine and on the right boot worn by Cruz the day of the shooting.

Cruz, 23, pleaded guilty last year to slaughtering 17 people on Feb. 14, 2018, when he opened fire at Marjory Stoneman Douglas High School.

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Sg.t Gloria Crespo holds up a magazine with a swastika etched on both sides

Sheriff's Office Sgt. Gloria Crespo testifies during the penalty trial of Parkland shooter Nikolas Cruz in the Broward County Courthouse in Fort Lauderdale, Florida, on Tuesday, Sept. 27, 2022. (Amy Beth Bennett/South Florida Sun Sentinel via AP, Pool)

The penalty trial will determine whether Cruz is sentenced to death or life in prison without the possibility of parole. 

Broward County Detective Nick Masters took the stand and told jurors that Cruz had searched online for how to buy a Nazi flag, for information on Adolf Hitler's birthday and how to get a swastika tattoo.

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He also searched for child pornography, Masters said.

On social media, he talked about a desire to murder Black people, described women as "less important than a dog," and bragged about killing 12 cats.

 "I am glad when animals die. It makes me happy," he wrote. 

Sgt. Gloria Crespo holds up Nikolas Cruz's rifle

Broward Sheriff's Office Sgt. Gloria Crespo testifies about the weapon used at Marjory Stoneman Douglas High School during the 2018 shootings. (Amy Beth Bennett/South Florida Sun Sentinel via AP, Pool)

During cross-examination, defense lawyer Nawal Bashimam asked Masters whether he had seen Cruz's Google searches seeking mental health treatment, which the detective acknowledged. "How do I help myself with these bad feelings?" Cruz typed into the search box.

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Circuit Judge Elizabeth Scherer only allowed prosecutors to introduce a small sampling of Cruz's online searches and comments, ruling that permitting more would be too prejudicial. 

Prosecution expert Dr. Charles Scott, a forensic psychiatrist, told jurors that the homicidal attack was driven by antisocial personality disorder, also known as sociopathy. 

Nikolas Cruz wears a navy sweater and a blue surgical mask pulled under his mouth

Nikolas Cruz is escorted into the Broward County Courthouse, Sept. 27, 2022. (Amy Beth Bennett/South Florida Sun Sentinel via AP, Pool)

The doctor said Cruz is capable of controlling his behavior but chooses not to because he has no regard for others.

Scott, of the University of California, Davis, spent three days interviewing Cruz. 

Jurors were also shown writings and drawings found in Cruz's cell in May in which he fantasized about committing future school shootings.

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Prosecutors have not argued that Cruz specifically targeted women or minorities.

The Fort Lauderdale trial will go dark until Monday due to Hurricane Ian's arrival in Florida.