Joseph was killed last May, two days after he applied to marry 21-year-old Christian, Neenu Chacko, a woman from a higher caste; he was from India's lowest dalit caste.
The prospective bride's brother Sanu Chacko is one of the 10 accused.
The judges described the crime as a clear case of an "honour" killing and said the only reason why they were not handing out death sentences was on account of the age of the accused and the fact that it was their first offence.
In court Neenu Chacko heard details of how Joseph was abducted and killed. She testified against her relatives. "This is a fight for Kevin," she told the media during the trial.
The couple began dating in 2016 after meeting at a bus stop on the way to a college in Kottayam where Chacko was doing a post-graduate course in geology and Joseph worked as an electrician.
On 24th May 2018 the couple applied for civil marriage. Four days later, Joseph's body was found in a stream. The court heard that Neenu Chacko's father – known as Chacko – had allegedly hired assassins with the help of a local politician. He was acquitted on murder charges for lack of evidence.
Although Dalits suffer relatively less discrimination and social ostracism in the southern Indian state of Kerala than elsewhere in the country, inter-caste marriage remains taboo for many people.
Indian media quoted Joseph's father as saying that although he would have preferred the death sentence for the ten men, he was satisfied with the life sentence.
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