JACKSONVILLE, Fla. -

It took a Clay County jury 45 minutes to convict a Naval Air Station Jacksonville employee of seven counts of sex crimes involving a child.

Jeffrey McDonald was also found guilty on two counts of tampering with a witness in the case.

Between January 2005 and March 2008, McDonald committed four counts of sexual battery and three counts of lewd or lascivious molestation on a child younger than 12.

In 2010, McDonald also secretly recorded a girl younger than 16 while she was undressing in a bathroom.

The 51-year-old was arrested in November. While in jail, McDonald made phone calls, sent letters and used two released inmates to mislead and encourage witnesses not to testify in depositions or at trial, prosecutors said.

McDonald's trial was originally scheduled for May but was delayed because of his tampering with the witnesses in the case.

"With this conviction, this monster can no longer hurt another child," said Assistant State Attorney James Colaw. "It took courage for this young victim to stand in front of her abuser and describe to the jury what happened to her. Hopefully, this verdict will give her some closure."

McDonald faces mandatory life in prison. He will be sentenced Sept. 12.