Can someone be deported while their case is back in criminal court?

Your question requires an attorney consultation. It is not a simple question that can be answered on this type of forum. There are many factors that would need to be considered and evaluated. What is his immigration status? Was he a Permanent Resident? Asylee? Undocumented? Was there a conviction? How did the case get sent back to criminal court? Was an appeal granted and the conviction overturned? Since we do not have all the facts, it is impossible to give a meaningful answers. I strongly suggest that you contact an experienced immigration attorney for a face-to-face consultation and give him/her all of the facts surrounding your friend's situation.