Rhonda Eisenberg. (Facebook/HO)

A middle-aged Colorado teacher had a baby with a 17-year-old student who was in her legal guardianship.

Police in Greeley say Rhonda Eisenberg, 44, admitted to having a sexual relationship with the teen in 2010, while he was living with her, and admitted to bearing his child, reported the Greeley Tribune.

The Spanish teacher had the boy in her care while his parents lived in Mexico, and told police she had sex with him "multiple times," according to the report. He cannot be named because the now-19-year-old was a juvenile at the time.

Co-workers and family became suspicious when Eisenberg gave birth to a Hispanic baby, police told the paper. An anonymous tip led cops to arrest her and book her into county jail on Tuesday.

She is charged with two counts of sexual assault on a child, one involving a pattern of abuse, and the other involving being in a position of trust. If convicted, she faces four to 12 years in prison on each count.