Police confirmed to the Los Angeles Times the investigation into the video, on which can be heard a parody of "Bad, Bad Leroy Brown" that refers to the Ferguson, Mo., 18-year-old and includes lines such as, "His brain was splatter on the floor."
The song was sung during a recent party hosted at the Glendale Elks Lodge by a retired LAPD officer, police said.
"I am aware of the video released via TMZ. Like many of you, I find it offensive & absurd. It does not reflect the values of the #," Chief Charlie Beck tweeted. "I have directed our Professional Standards Bureau to look into this & determine if any active department employees were involved."
Video of the party and singing was first sent to TMZ.
If investigators find that any current officers attended "and misconduct took place, a formal investigation will be opened," said Jane Kim, a spokeswoman for the LAPD.
Some of the changed lyrics to the song released by Jim Croce in 1973 include:
"Michael Brown learned a lesson
about a messin' with a bad … police man
And he's, bad, bad Michael Brown
Baddest thug in the whole darn town
Badder than an ol' King Kong
Meaner than a junkyard dog
Two men took to fightin'
And Michael punched in through the door
and Michael looked like some old Swiss cheese
His brain was splatter on the floor."
The preliminary investigation will begin as soon as Tuesday, police said.