Deerfield Academy is still investigating a former teacher accused of having sexual contact with a student during his tenure, even though an alumnus has retracted public comments he made about the instructor. In a statement last month, the school said retired teacher Peter Hindle admitted to sexual contact with a student. Ian Hammon, 41, a Deerfield graduate, later told the Globe that Hindle massaged his legs in his dorm in 1988. Hammon has since retracted a separate, written statement about the encounter on his blog. In a statement Thursday, Deerfield said, “We are aware of Mr. Hammon’s retraction, but our investigation continues.” A school spokesman declined further comment. Hammon has not returned subsequent calls from the Globe seeking comment