NY Giants Linebacker Michael Boley -- Under Investigation for Child Abuse

NY Giants linebacker Michael Boley -- who signed a $25 million contract in 2009 -- is being investigated for allegedly abusing his 5-year-old son earlier this year ... TMZ has learned.

According to the official incident report, taken by the Gadsden Police Department in Alabama -- Boley is accused of the repeated willful abuse of a child under 18 from May 30 to June 5.

Officials will not release details surrounding the nature of the alleged abuse.

A rep for the Gadsden PD tells us the case was investigated and has been handed over to the District Attorney's Office, which will present the case to a grand jury. The grand jury will then decide if there is enough evidence to formally charge Boley with a crime.

Boley's attorney, Randall M. Kessler, tells TMZ ... "These allegations were brought to our attention along with outrageous monetary demands in a contested child support case which she filed over a year ago."

Kessler added, "At final trial about a month ago, she did not seek an order restricting visitation. The only relief she requested from the judge was that child support be more than quintupled to, in her words, 'increase her lifestyle.'"

In light of the allegations, another woman who has a 2-year-old child with Boley, has filed court papers in Georgia asking a judge to require the NFL star to be supervised when spending time with their child.