Combined with the quote you posted in response to my comment, this does make the article (which didn't load for me) seem confusing. One one hand the fifth hitman 'eventually told the police', but on the other hand 'he told the target to fake his own death, which eventually led to the police finding out about the plot'. On balance it seems like hitman 5 didn't initiate contact with the police, but confessed when caught.
It's literally right there in the article..
> The contract finally came to the fifth hitman, Ling Xiansi, who eventually told the police.