In a landmark decision in post-apartheid South Africa, four men were given 18 years in jail on Wednesday for stoning and stabbing to death 19-year-old Zoliswa Nkonyana for living openly as a lesbian.

A crowd outside the court in Cape Town township cheered and danced after the sentencing was announced, the BBC News reported.

Mbulelo Dama, Lubabalo Ntlabathi, Sicelo Mase and Luyanda Londzi -- juveniles when the crimes were committed - were convicted of Nkonyana's murder last year, the South African Broadcasting Corporation reported.  Five others were acquited.

While rights groups complained throughout the trial that proceedings were taking too long -- they took almost six years -- and involved more than 40 postponements, the verdict was a watershed, an official at a South African NGO that fights discrimination against gay, lesbian bisexual and trans-gender people told msnbc.com.

"It is the first case in South Africa where sexual orientation and identity was named and recognized as an aggravating factor in a murder trial," said Marlow Newman-Valentine, Deputy Director of Triangle Project.

The magistrate in the case said hatred and homophobia were clearly the motive for the killing, and Wednesday's sentence was meant to send out a signal that violence based on sexual orientation will not be tolerated, the BBC reported.

South Africa's constitution prohibits discrimination on the basis of sexual preference but homophobia is rife in the country. In addition, the country's female homicide rate six times the world average, according to a June-2011 study in The British Journal of Criminology.

Activists were "still hugely concerned" with the South African police's effectiveness when it came to dealing with these sorts of crimes, and their unwillingness or inability to follow proper procedures in many cases, he said.

"As the Triangle Project we are extremely happy about the outcome of this particular trial but we have a long way to," Newman-Valentine said.

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