A retired swim coach with Mt. Pleasant Public Schools and the city recreation was arrested Wednesday following an investigation into whether he engaged in sex with a child. 66-year-old David E. Alsager of Mt. Pleasant was arrested and booked Wednesday before being released on a $20,000 bond. A press release from the Mt. Pleasant Police Department said that it was reported Nov. 30 of last year that the incident involved a 12-year-old girl.