Yung Ching-ching talks about the five major doubts in the body hidden in the cardboard box case, hinting that the murderer is Lam Kwok-wan?

The 1974 "Happy Valley Cardboard Box Corpse Case" was a sensational unsolved case in

...would an ordinary person know that there was a telephone in the factory? Moreover, there were two fruit stalls outside the company, and both fruit stalls had telephones. Normally, one would borrow a telephone from a fruit stall instead of walking into an unfamiliar environment to borrow a telephone.