Saheed Vassell had three run-ins with cops as an “emotionally disturbed person” — including an incident during which he ate rocks in the street while not wearing pants, The Post has learned.

Vassell was taken in for psychiatric treatment following that episode, which took place in 2008 and began when he was spotted running through traffic on Brooklyn’s Atlantic Avenue clad in a pair of boxer shorts, a high-ranking NYPD source said.

Vassell later lay down in the street, banging his head on the pavement and eating rocks, the source said.

He was also hospitalized in 2011 when EMS responded to a 911 call from Vassell’s mom, who said he hadn’t taken his medication and was violent and irrational, the source said.

It’s unknown whether Vassell received in-patient treatment either time, but Vassell’s mom called 911 again in 2014 when he refused to take his meds, the source said.

It’s unclear if he was taken to the hospital following that incident.

Vassell’s rap sheet lists 28 arrests and dates to 1999, when he was busted on a charge of first-degree gang assault.

He was also charged with assault in 2005, 2006 and twice in 2013, with the latter incident that year marking the last time he was arrested.

Vassell, who was never sentenced to time in state prison, was also charged with possession of a firearm in 2010, the source said.

A 2005 arrest for armed robbery was voided, likely because the victim declined to testify, and two arrests in 2007 — for grand larceny and possession of stolen property — were sealed, which happens following acquittal or the dismissal of charges.

He also racked up a series of arrests on minor offenses including criminal mischief, petit larceny, driving without a license, pot possession and disorderly conduct.