An unarmed security monitor who critics say could have stopped the Florida high school massacre was suspended last year for sexually harassing students.

The South Florida Sun-Sentinel reported that 39-year-old Andrew Medina was suspended for three days after an investigation corroborated allegations by two female students.

Records obtained by the paper say Medina asked one student out and made a lewd comment to another in February 2017, a year before the attack that left 17 dead.

The students' ages were not released.

A disciplinary panel recommended in October that Medina be fired, but the district instead suspended him.

Medina spotted shooting suspect Nikolas Cruz entering campus on February 14 and recognised him as a potentially dangerous former student, but didn't stop him.

The family of one of the Florida high school shooting victims said she was one of the girls harassed last year.

The father and brother of Meadow Pollack told The Associated Press that she was one of the Marjory Stoneman Douglas students Andrew Medina harassed.

Andrew Pollack and his 20-year-old son Hunter Pollack said they didn't learn until after the February 14 shooting that Medina harassed Meadow, then 17.

Hunter Pollack said a Broward County schools investigator spoke with him.

Andrew Pollack said his ex-wife never told him about Medina, but reported it to the school.

The 39-year-old Medina didn't return a call to Associated Press.