As an Edmonton police officer accused of assault and racism returns to patrol duty, three human rights groups are calling for a public inquiry.

"The fact that Const. [Nathan] Downing — who has a history of using excessive force during arrests, and who arrested a key witness just prior to his own disciplinary hearing — has been permitted to quietly return to active duty is incredibly concerning," said Mustafa Farooq, executive director of the National Council of Canadian Muslims (NCCM), in a joint news release issued Monday with the Canadian Anti-Hate Network and Hate Free Yeg.

"It means that there is a fundamental issue with the investigative process here."

Downing — who was previously convicted of using unlawful force under the Police Act in a separate incident — is accused of using Islamophobic language and excessive force on a handcuffed suspect during a March 2015 arrest.

The arrest left Nasser El Hallak with facial fractures and other injuries, a disciplinary hearing heard in May.

The hearing was adjourned after a key witness to the alleged assault, Crystal Fox, testified that Downing had arrested her two weeks before she was scheduled to testify. Downing had charged Fox for allegedly driving with a suspended license.

The revelation prompted NCCM and other rights groups to call for Downing's re-assignment.

"Anyone who cares about the basic way that our legal system is supposed to unfold should recognize pretty clearly that there is a problem when a police officer can arrest a witness in his own disciplinary hearing," Farooq said in an interview Monday.

He said an inquiry would have to be initiated by the provincial justice minister under the Public Inquiries Act.

Stop not targeted

Downing, who went on pre-approved leave while police investigated the allegations against him, returned to frontline patrol duties at the end of June.

"I am limited in what I can share given the ongoing Professional Standards Branch investigation, but I can tell you that the investigative steps to date show that the traffic stop conducted on Ms. Fox was not targeted," spokesperson Cheryl Sheppard wrote in an email to CBC.

Mustafa Farooq with the National Council of Canadian Muslims says recommendations from an inquiry would set parameters around witness interference. (Peter Evans/CBC) "As a result, Const. Downing has returned to his regular duties."

Bernie Farber, chair of the Toronto-based Canadian Anti-Hate Network, said Downing's matter has been mismanaged.

"Given all the mistakes made during the course of this case an inquiry would both bring answers and give needed direction for the future," Farber said in the news release.

At the disciplinary hearing in May, Nasser El Hallak said the 2015 arrest left him with facial fractures and nerve damage to his face and hand.

Downing, who denies the allegations stemming from the 2015 arrest, said he delivered one punch during the struggle to subdue El Hallak.

'Public deserves to know'

The decision to allow Downing to resume patrol duties continues to damage the confidence some marginalized communities have in police, Bridget Stirling, a member of Hate Free Yeg, said Monday.

"I think it's destructive to that work that's being done," Stirling said. "I think there are deeper questions in terms of how EPS is handling internal investigations, how they're managing these situations, that really need that public transparency and accountability that an inquiry would bring."

In May, police Chief Dale McFee delivered a formal apology for wrongs committed against the city's LGBTQ2S+ community. He expressed strong support for the service's new Indigenous strategy unveiled in March.

Edmonton lawyer Avnish Nanda said the allegations undermine the public's trust in the ability of the Edmonton Police Service to investigate the conduct of its officers.

"The public deserves to know why the EPS and Const. Downing made the decisions that it did, and why Const. Downing happened to stop and charge the witness right before his disciplinary hearing," Nanda said.

Last month an Edmonton police officer at the centre of a violent arrest caught on video was removed from patrol duties. It's one of several incidents that have surfaced recently involving Edmonton police and accusations of excessive force. While the officer has been suspended without pay, other officers facing similar accusations have remained on active duty.

In an unrelated disciplinary hearing in September 2015, Downing was found guilty of unlawful or unnecessary exercise of authority after hitting a fleeing suspect with his police van. The suspect's ankle was broken.

An arrest warrant was issued for Fox after she failed to show up for her own court date in June.

Downing's partner on the night of El Hallak's arrest, Const. Nicholas Talvio, also faces charges at the disciplinary hearing which is scheduled to resume on July 24.