A man in the US is facing charges of child endangerment after allegedly tattooing the backside of a one-year-old girl.

Police say Lee Deitrick tattooed the letter "A" on the girl, who is not his child, when she visited his home in Louisville last November.

There's no explanation as to why the 20-year-old chose that letter when he permanently tattooed the girl, the Los Angeles Times reports.

Authorities say there's no evidence the girl's mother gave Deitrick permission to tattoo the child.

Deitrick faces up to five years in prison if convicted.