In addition, tThe policeman said that they had investigated similar cases of counterfeit trademark liquor before, so they doubted these Moutai liquor.have doubts whether these bottles of Moutai wine are real.

I deleted "in addition", because this is your first sentence, and no other facts have been established. Also, I got rid of similar for the same reason. Similar to what?

Mr. Zhou said that these bottles of Moutai were bought from a net site for 1purchased online for only 1,499 yuans per bottle.

You should explain who Mr. Zhou is.

But wWhen the police wanted to see that net site, Mr. Zhou said thatere investigating the website from where Mr. Zhou purchased the Moutai, the net site was gone.had disappeared.

This situexplanation made the police even more doubt more.ful regarding the authenticity of the Moutai.