A Philadelphia police homicide detective is under internal investigation for allegedly calling a colleague a "filthy savage" and a "grotesque, primal animal" in a letter about leaving leftover food beneath a work station, a situation that devolved into a series of racially charged insults, Police Commissioner Richard Ross said Tuesday.

Ross said the letter, written by a white homicide detective and 22-year veteran of the force, was taped above a trash can in the Homicide Unit in recent days. It was not addressed to any specific officer, Ross said, but other members of the unit, concerned about the language in the letter, made copies and shared it among colleagues.

Among other insults, the letter says: "As I'm sure you were not burdened by significant schooling, and were birthed to an alcoholic, absent father and a rancid whore of a mother, you are simply ignorant of the fact that you are little more than an upright animal," according to a copy obtained by the Inquirer and Daily News.

"The tone and the tenor of the letter raise questions about whether racial bias or inappropriate biases … were involved with the message," Ross said at a news conference. "Some of the references in the letter are very troubling."

Rochelle Bilal, president of the Guardian Civic League, an organization that represents black officers, said Tuesday that she believed the letter's language was "basically geared toward the stereotype of black people and black families."

"Anybody in this institution of service to the community that makes any of these statements like this shouldn't be on the job," Bilal said Tuesday.

John McNesby, president of Fraternal Order of Police Lodge 5, said of the letter: "There's no place for that. If you have a problem with somebody … you should address it personally."

The commissioner's announcement came about eight months after a group of black narcotics officers sued the Police Department over allegations of racial discrimination. And two years ago, the department came under intense scrutiny when photos of an officer's tattoo — which critics said resembled a Nazi eagle — surfaced on social media.

Ross said the situation Tuesday was "totally different" from the narcotics lawsuit at least. Still, he said the Police Department administers training intended to enable officers to recognize their own biases in order to avoid acting on them. He also acknowledged that the letter contained phrases that "cause me deep concern."

"We do have a higher standard that we have to live up to," Ross said. "And so, when people want to hold us to a higher standard, I think they're right to do so."

Bilal shared with the Inquirer and Daily News a copy of the letter, which she said she received Tuesday. It is addressed only to "fellow coworker" and is signed by Detective Jimmy Crone. It begins by complaining about leftover ribs in a wastebasket beneath a work station, but in the next sentence says: "Now, in that I have a sense of etiquette and social fluency instilled in me from my upbringing by traditional, caring parents, I am offended by this."

After insulting the unnamed colleague's parents and education level, the letter says: "I am not in any manner trying to embarrass you, just the opposite; I'm here to offer my guidance and assistance in helping you make the difficult transition from a grotesque, primal animal to tolerable coworker."

Crone could not immediately be reached for comment.

Ross said that Crone admitted writing the letter, but that it was not clear if Crone knew who had created the mess that evidently enraged him. The commissioner did say he was "perplexed" that a seemingly mundane office dispute would generate such rancor from a seasoned detective.

"I just think the language [of the letter] did not, in any way, fit the offense," Ross said.

He said black members of the Homicide Unit — which he described as about 50 percent African American — were offended by the letter's wording, "some of which historically has references to African Americans in particular."

The commissioner said Crone was generally well-respected and did not appear to have been the subject of many complaints during his two-decade career, 12 years of which he has spent in homicide. Among his assigned cases during that time, news reports show he helped to investigate a faith-healing couple charged with allowing their infant son to die instead of seeking treatment, and a 25-year-old man charged with killing two women — one of whom was known as "Grandma" — over their alleged drug stash.

Ross said Crone would be placed on administrative duty pending an investigation by Internal Affairs.

Correction: An early version of this story incorrectly reported that an officer who had been criticized for a tattoo was still on the police force. That officer resigned in March, according to Police Commissioner Richard Ross.