Complex sentence: The investigators at first were not convinced of Liang's story but the boy claimed that Yong had invited him to his apartment by offering him a job but once he got there, Yong tried to strangle him and that he was into unconsciousness three times.
Split into simpler sentences: The investigators at first were not convinced of Liang's story but the boy claimed that Yong had invited him to his apartment by offering him a job. But once he got there, Yong tried to strangle him and that he was into unconsciousness three times.