BANGOR – A local man pleaded guilty Thursday to assaulting his infant son but will spend only six months in prison because of a plea agreement.

Joshua Jackson, 21, of Old Town originally faced three charges, two counts of aggravated assault and one count of assault, resulting from an incident in December 2003 while he was living in Bangor with his 3-month-old child.

The two aggravated assault charges, which could have meant 10 years in prison, were dismissed, and Jackson was sentenced to three years in prison on the final charge with all but six months suspended and one year of probation, according to Michael Roberts, Penobscot County deputy district attorney.

Because Jackson’s son was under the age of 6 at the time of the assault, the crime is considered a felony.

The sentence was handed down by Justice Joseph Jabar, sitting in Penobscot County Superior Court.

Officials and relatives became concerned for the infant’s well-being after noticing the child was lethargic and had bruising on his face in December 2003, according to Roberts.

Medical examinations conducted in January 2004 determined the child suffered from bleeding on the brain. This condition most often is associated with “shaken baby” syndrome in infants, Roberts said.

Jackson acknowledged being rough with his son at times, but denied shaking the child, his attorney, Brad Macdonald of Bangor, said.

“[Jackson] admitted to aggressively playing with his son, but in a playful manner,” Macdonald said. “This is the case of a young father. He admitted to maybe playing a little to roughly for a child of his son’s age.”

The defense attorney said he was pleased with the reduction in counts and the reduced sentence.

“The nastiest allegations were dismissed because of the dispute in the medical investigation,” Macdonald said in a telephone interview after the court hearing on Thursday.

The attorney said there were questions about what could have caused the bleeding in the infant’s brain and evidence linking Jackson to the condition.

Jackson was on probation in connection with charges in New Hampshire at the time of the incident. Because of the assault charges in Maine, he had to return to New Hampshire to serve a year for violating his parole.

Because Jackson had served a year in New Hampshire, the six-month sentence he received “was appropriate,” Roberts said.

Tests have determined that his son, now 2, doesn’t appear to have any permanent medical problems.