Terminate employee due to fraud

Hi, We are an IT consulting firm . We hired consultant after our internal interview and client interview. Both interviews were done on phone so we didn’t see the candidate. After he joined, client told that he is fake. He cannot perform or answer any questions which were asked in interview. His accent is totally different than during interview. We have to terminate him without paying as we will not bill to client. It’s around one month billing. Can you pls advice if we can do this or we have to give him notice period (15days) per our offer letter and what steps we should take against him Thx Amit