CHICAGO (Reuters) - The Chicago police officer who shot a black teenager last year pleaded not guilty to murder on Tuesday, as Mayor Rahm Emanuel cut short a vacation to return to the city to deal with the fallout from two more fatal police shootings over the weekend.

Meanwhile, protesters demonstrated outside the Cuyahoga County prosecutor’s office in Cleveland, a day after a grand jury decided not to charge two white police officers in the 2014 shooting death of Tamir Rice, a black 12-year-old boy who was playing in a park with a replica gun that shoots plastic pellets.

Tensions over race and policing in Chicago and Cleveland come amid intense scrutiny of police killings in the United States over the past 18 months, especially of black men. Protests have taken place around the country and the issue has fueled a civil rights movement under the name Black Lives Matter.

Chicago Police Officer Jason Van Dyke, who is white, faces six counts of first-degree murder and one count of official misconduct for killing Laquan McDonald, 17, in October 2014. He pleaded not guilty to all charges on Tuesday at the Cook County criminal court in Chicago. Van Dyke’s lawyer said he may ask for a change of venue.

“We’re certainly going to explore every opportunity we have in order for my client to have a fair trial,” attorney Daniel Herbert said after the hearing.

The release last month of a video of the shooting, which shows Van Dyke shooting McDonald 16 times, set off a wave of protests and calls for Emanuel’s resignation.

McDonald’s great uncle, Marvin Hunter, said after the hearing that Van Dyke’s trial should be televised to ensure fairness.

Chicago police Officer Jason Van Dyke (R), leaves the courtroom after a hearing with his attorney Daniel Herbert at Leighton Criminal Court Building in Chicago, Illinois December 18, 2015. REUTERS/Zbigniew Bzdak/Pool

Over the weekend, another Chicago police officer fatally shot two black people, setting off more protests, and prompting Emanuel to cut short a family vacation to Cuba.

Bettie Jones, 55, a mother of five, and college student Quintonio LeGrier, 19, were killed early on Saturday by an officer responding to a call that LeGrier was threatening a family member with a baseball bat. Police said Jones was killed by accident. [L1N14H0YL]

A vigil by former students is planned for LeGrier on Tuesday evening at Gwendolyn Brooks College Preparatory Academy, a selective enrollment high school LeGrier had attended, said Daniel Bauer, assistant principal.

“(Quintonio) was a good kid,” said Bauer, who had run with LeGrier and other students in the Chicago Marathon to raise money for clean water for children in Africa. “This is a tragic loss.”

LeGrier’s father, Antonio LeGrier, has sued the city, both for wrongful death and for false arrest, saying he was detained and interrogated by the police after the shooting and not allowed to stay with his dying son.

Antonio LeGrier told CNN on Tuesday that the officer, who was white or Hispanic, knew he had made a mistake after the shooting and exclaimed, “I can’t believe it. I thought he was coming at me with that bat,” and “Fuck no, no.”

In Cleveland, some protesters took to social media on Tuesday to ask Cleveland Cavaliers basketball star LeBron James not to play to help pressure the U.S. Department of Justice to get involved in an investigation. A representative for James was not available for comment.

A group of about 75 protesters unsatisfied with the grand jury’s decision in the Rice case listened to speeches outside the Cleveland prosecutor’s office on Tuesday. They then marched through downtown Cleveland chanting “No justice, no peace, no racist police.” The demonstration was peaceful and no arrests were reported.

Cleveland police will review the fatal shooting of Rice from start to finish to determine if the two officers involved or others should face disciplinary action, officials said on Tuesday.

In Chicago, about 20 protesters gathered outside Mayor Emanuel’s house on Tuesday afternoon, according to CBS Chicago. There is also a protest planned at City Hall on Thursday.

Protests over the shooting of Laquan McDonald led to the resignation of Chicago’s police chief and a Justice Department probe into whether the city’s police use lethal force too often, especially against minorities.

Van Dyke’s case was assigned to Cook County Circuit Judge Vincent Gaughan. Van Dyke’s next hearing is on Jan. 29.