KANSAS CITY, Mo. -- It may have been a pin prick, but a prosecutor says it's also a punishable offense.

A city prosecutor in Riverside, Mo., charged a high school student with assault for allegedly poking another student with a pin used to prick fingers before blood is drawn.

The pin had been snatched during a blood drive, and it may have been used on a donor, city prosecutor Mark Ferguson said. If it was used on a donor, the student who was poked could have gotten a disease, including HIV or hepatitis.

"I think he was just messing around," Ferguson said of Adam R. Prentice, 18, who is accused of poking a 16-year-old classmate. "But our concern is, we don't know where that needle has been."

According to police reports, Prentice cut the other student on the leg March 20 as the student sat at a computer at Park Hill South High School in Riverside, a Kansas City suburb.

Prentice told police that he got the pin, which is used to prick a finger to draw a drop of blood, from a student who had taken it from a table during a blood drive March 12. Prentice said the needle was clean.

A blood test shortly after the incident was normal, the victim's father told The Kansas City Star.

If Prentice is found guilty, he faces up to 90 days in jail and a $500 fine.