I'm surprised so many of you are telling him to snitch, talk to him about it Lillica and if he fails to make amends THEN it's time to go to the professor.
Do not do his work for him under any circumstances.
You are told at the beginning of the year do NOT directly copy wiki. You can use it to find resources, but if you copy it, it's up to the professors mercy. They do not take kindly to that.
It's flat out insulting to the people you are working with to do that, and disrespectful to your professor.
I would take his section of the paper to the professor, show him the copies, and ask his opinion on what to do.
If this guy can't be decent enough to give you SOME effort in group worth, he's not worth having in the group.