By Miguel Marquez

CNN

(CNN) -- New video casts a glaring light on Baltimore Police practices as the department and city grapple with a distrustful public and record-setting violent crime.

The video reportedly shows what happened during what might otherwise have been a typical drug bust on January 24, 2017. Released by the Office of the Public Defender, the video purports to show a Baltimore police officer planting evidence at the scene of a drug arrest.

The Baltimore Police Department has now launched an investigation and held a news conference releasing several other videos while offering a basic timeline of events.

Baltimore Police Commissioner Kevin Davis, seeking to allay public concern, called it "a serious allegation of police misconduct," saying, "our investigation will ultimately determine what happened, it will identify if any criminal misconduct took place, any administrative procedures were violated and we're determined to get to the bottom of it."

The video, recorded on police body-worn cameras, shows the officer placing a plastic bag into a food can then partially hiding it under a piece of debris. Thirty seconds later the audio begins and the officer says, "I'm going to check here. Hold on," as his colleagues laugh. The officer then gives a cursory look at other items in the debris-strewn lot and appears to stumble onto the drugs in the can.

"Yo!" the officer shouts at his colleagues as he holds up the small cellophane bag containing several pills. One of his police colleagues only shouts back "What's up?" The video ends a few seconds later.

As the officer searches the lot for evidence, one of his colleagues can be heard saying, "Is that 30?" which was possibly a reference to the way the body-worn cameras used by Baltimore police operate; they record 30 seconds of video, without sound, before the camera is actively turned on by the officer, according to the manufacturer, Axon. Referred to as a buffer, it's meant to capture crucial evidence that might occur just before an officer activates his camera.

Davis said of the video, "I saw video footage of officers apparently placing evidence and recovering evidence in a way that initially based on what I saw, very narrowly, inconsistent with the way police officers do business."

One officer in the video has been suspended and the other two placed on administrative duty pending an investigation by the department's Office of Professional Responsibility.

Police said the arrest involved a drug sale that led to the discovery of two bags of heroin in gel capsule form. One bag was tied off and the second bag had been opened and recovered by officers at the scene. The police chief said, "It's certainly a possibility that we're looking into to see if the officers in fact replaced drugs that they had already discovered in order to document their discovery with their body-worn cameras on."

Baltimore's Public Defender's Office said it turned over the video to the Baltimore City State's Attorney's Office, which is responsible for prosecuting those charged with crimes in the city.

In a statement, the public defender said the "prosecutor in the case claimed to be 'appalled' by the video and dropped the charges in the case." The Baltimore City State's Attorney's Office added in a statement, "Our office immediately implemented established protocols to not only refer this matter to the Internal Affairs Division of the Baltimore Police Department but began identifying active cases involving these officers."

The Public Defender also says the officer in question is a witness in 53 open cases and was used recently as a witness by a prosecutor in the Baltimore City State's Attorney's Office despite knowing about the questionable behavior captured on video. The Baltimore City State's Attorney's Office did not respond to questions about why the officer in question had testified as a witness in at least one subsequent trial.

In a statement, Debbie Katz Levi, who leads the Public Defender's Special Litigation Section, said, "Officer misconduct has been a pervasive issue at the Baltimore Police Department, which is exacerbated by the lack of accountability. We have long supported the use of police body cameras to help identify police misconduct, but such footage is meaningless if prosecutors continue to rely on these officers, especially if they do so without disclosing their bad acts."

Gene Ryan, president of the Fraternal Order of Police, Baltimore's main police union, urged patience. "I'd love for everyone not to jump to conclusions" he said, "and wait for the outcome of the investigation. It will all come out."

Baltimore Police have been rocked by controversy and stubbornly high crime rates since the death of Freddie Gray in April 2015. Six officers were charged criminally in connection with his death. The trials ended in either a hung jury, or officers were found not guilty or had charges dropped after the state's attorney was unable to proceed with prosecution.

This year, deaths due to gun violence in the city are up 21% over last year, with 186 killed so far, according to the Baltimore Police. If the pace of killings continues, the city is on track to set a record.

Long plagued by charges of corruption, Baltimore's police department has struggled to win public confidence. Last March, seven Baltimore officers were federally charged with robbing citizens, filing false reports and claiming overtime fraudulently. Shortly after, in ending plainclothes policing, the police commissioner told the Baltimore Sun he was concerned their methods "accelerated a cutting-corners mindset."

Since 2011, Baltimore has paid out more than $13 million to settle lawsuits alleging police misconduct. Last April a federal judge approved a consent decree after a Justice Department report found a wide racial disparity in the way the Baltimore Police Department treats its citizens.

This latest episode is another blow for a city still struggling to its feet.

"There is nothing that deteriorates the trust of any community more than thinking for one second that uniformed police officers and police officers in general would plant evidence of crimes on citizens" said Davis. "That's as serious as it gets."