The following is the caption from the photographer regarding the person here depicted:
"The guide/pamphlet for Gesu Church in Milwaukee, WI indicates this is St. Leo the Great, but I think it might be St. Gregory the Great. One of Gregory the Great's common symbols is a dove whispering into his ear. I wasn't able to find any references to a bird or dove being a symbol of Leo the Great. The tiara could be associated with either Gregory or Leo, but a double cross is usually seen with Gregory and a triple cross with Leo, so that doesn't help my argument much."