BATON ROUGE - A friend of the family of a Baton Rouge police officer shot and killed Sunday confirms he posted an emotional Facebook message just days ago about the challenges of being a police officer.

Erika Green told The Associated Press Sunday that she is friends of the family of Montrell Jackson, the slain officer, and that she saw the message on his Facebook page.

Heartbreaking Facebook post from Montrell Jackson, one of the cops killed today. (via @ChristeeAtwood) #BatonRouge pic.twitter.com/GgW5LdCct4

— justin kanew (@justin_kanew) July 17, 2016

A screenshot of the image has been widely circulating on the internet. The date was July 8, just three days after a black man was shot and killed by police in Baton Rouge, touching off a tense week between police and the city's African-American population.

It is no longer on his Facebook page.

In the message, Jackson says he is physically and emotionally tired. He says while in uniform he gets nasty looks and out of uniform some consider him a threat.

A GoFundMe campaign was already set up Sunday night for Montrell's family. It had already surpassed $16,000 in donations by 7 p.m.