The next day was the last day the crew and Jia were to be staying for this trip. The flight back home to Beijing would be in the early hours of the next day and everybody took this time to rest.
After more investigation, Lei Honghui found out that Xin Manchu indeed had the previous knowledge of Wan Guanting's hypertension so him asking for the cold medicine from the hotel's staff wasn't a coincidence. Currently, the version the police believed was that after mixing the cold medicine, Xin Manchu climbed the balcony from Zeng Shan's balcony to assure himself of Wan Guanting's death.
But he might have realized that he was still breathing and alive and in a state of panic, he used the pillow to suffocate him and kill any further possibility of living.