With only a week left until the election, Vice President Kamala Harris plans to give a speech on Tuesday in Washington that she is billing as the closing argument of her presidential campaign.

Her courtroom approach decades ago could shed light on how she will make her final plea to voters. Long before Ms. Harris was vice president, she was a young lawyer in the San Francisco Bay Area, asking juries to convict people accused of murder and rape.

The New York Times unearthed transcripts from six felony trials that Ms. Harris prosecuted to review her closing statements. They come from a rare stretch in her professional life when few eyes were on her: She was assigned dozens of felony cases when she was an Alameda County prosecutor from 1990 to 1998, but only a fraction of them went to trial.

The transcripts offer one sense of how Ms. Harris thinks and tackles problems, revealing a persuasive and disciplined prosecutor who was able to minimize facts that didn’t help her case. She also positioned herself as a voice for women, a stance she has maintained throughout her rise in politics, and showed little patience for male defendants who acted with false bravado and preyed on the vulnerable.

Sharmin Bock, an attorney who worked closely with Ms. Harris in Alameda County, recalled sitting on the courthouse steps with Ms. Harris in the 1990s to discuss trial strategies. Ms. Bock says she sometimes sees glimmers of those days as she watches Ms. Harris on the campaign trail. “I see Kamala talking to her jury,” she said.

‘Showing the math’ to jurors