He'll most likely need to apply for rehabilitation before he can be issued a visitor visa. When he applies for a visitor visa, he needs to be 100% honest about the criminal charges and also about his deportation from the US. The US and Canada share information extensively. If he leaves this information out of his application - CIC will find out, refuse his application and then ban him from Canada for 5 years for misrepresentation. If he needs to apply for rehabilitation, CIC will let him know.
Information about how to apply for a visitor visa is here:
http://www.cic.gc.ca/english/information/applications/visa.asp
Information about how to apply for rehabilitation is here:
https://www.canada.ca/en/immigratio...n-inadmissible-persons-criminal-activity.html