The dismal conviction rate leaves victims feeling helpless, Ms. Jewkes said.

“Many women wonder why they should bother to report,” she said.

Like many others in Bredasdorp, a dusty, remote farming town about 100 miles southeast of Cape Town, Ms. Booysen had a difficult childhood. Her mother died when she was young, and she was passed between relatives and bounced in and out of foster homes, relatives and neighbors said.

She dropped out of high school, and like many young people here, where jobs are hard to come by but alcohol and drugs are omnipresent, she spent her days idly drinking cheap beer and wine with friends. The day she was attacked was no different.

On the afternoon of Feb. 1, Ms. Booysen was at a neighborhood bar, witnesses said. So was Mr. Davids, though the two had not arrived together, and were not seen drinking together, the witnesses said. Another young man, Johannes Kana, was also there.

Early the next morning, Ms. Booysen was found at a construction site near her house, bleeding and near death. She was taken to the hospital but died that day.

What happened after she left the bar is disputed. In an interview, Mr. Davids said that he saw Ms. Booysen at the bar, but did not drink with her, did not know the people she was with and did not see when she left. He said he left the bar to continue drinking at a friend’s house. Mr. Kana admitted raping Ms. Booysen, according to the government, but denies killing her. He has been charged with rape and murder and is now the only suspect on trial.