'Teen Mom' Jenelle Evans Husband David Eason Allegedly Injured Her 14-Year-Old Son

We're now learning more about what led to the child abuse charge leveled against Jenelle Evan's husband, David Eason ... who allegedly roughed up Jenelle's 14-year-old son, Jace, leaving marks on his body.

According to court docs, obtained by TMZ, Eason is being accused of inflicting physical injury on Jace ... causing "marks on the right arm and left and right side of the neck." The documents say the injuries weren't sustained by accident.

While the docs don't exactly explain what happened, the timing of the alleged incident is interesting ... stating the whole thing went down on September 28.

September 28 is also the same night Jace ran away from home, slipping out his bedroom window and into the woods nearby. It's possible Jace and David had some sort of exchange before Jace left the property. Remember, we were told there's video both cops and child protective services have in their possession ... which could've led to the charge.

Jace was eventually located, after cops got involved, though the September 28 disappearance marked his 3rd runaway incident in about a month.

It doesn't appear Jace is currently in Jenelle's custody, and it's believed he's with his grandmother, Jenelle's mom, Barbara.

As for their part, Jenelle released a statement on Instagram shortly after TMZ broke the story of David's misdemeanor child abuse charge. Evans wrote, "I do not trust anyone around me ... I have no idea what human being I can trust anymore, not even my own blood."