Brooklyn prosecutors dropped four murder charges Friday against a man accused of setting a fire in 2006 that killed two women and two kids, admitting they lacked evidence.

Samuel Martinez, 40, was charged in 2012 with killing a boy and girl, their mother and another tenant by setting the blaze at a Crown Heights apartment building.

He was originally remanded without bail but that amount was reduced to $1 last month after the case weakened.

“There are no eyewitnesses or physical evidence,” prosecutor John Holmes said in court.