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PHILADELPHIA (CBS) — A Philadelphia homicide detective is under internal review after admitting to penning an offensive letter to a colleague who reportedly left rib bones from dinner in a shared workspace trash can, allegedly calling him “grotesque” and a “filthy animal.”

Commissioner Richard Ross told reporters on Tuesday that the 22-year veteran, who has a clean internal file, has been removed from street duty until further notice while the investigation continues. Ross says it stemmed after the homicide detective taped a letter to a trash can complaining about the bones that were discarded.

Credit: Letter obtained by CBS3

“The tone and the tenor of the letter raises questions about whether racial bias or inappropriate biases were involved in the message. Some of the references in the letter are very troubling,” said Ross.

Ross said the letter contained offensive language toward another detective in the homicide unit.

“It’s because of some of the language that’s in here, some of which, historically, has referenced to African-Americans in particular, that’s why it’s particularly concerning,” stated Ross.

(credit: CBS3)

The letter reads in part: “As I’m sure you were not burdened by significant schooling… you simply are ignorant of the fact you are little more than an upright animal.”

“There’s no indication he knew who he was addressing,” said Ross.

“It’s a bunch of drama to be honest with you,” said FOP president, John McNesby of the letter. “It’s filled with all kinds of nasty sayings and stuff. It’s just not the time or place to be doing that especially in the work place. “

Ross said the detective owned up to writing the letter after being confronted about it.

“When approached, he said he wrote it,” said Ross. “I’ve never really seen it done quite like this so I’m deeply disturbed and dismayed by it.”

What is clear, Ross says, is his commitment to upholding the integrity of the department.

The name of the detective who wrote the letter has not been released. The detective faces possible dismissal.