CLEVELAND, Ohio — Cleveland Mayor Frank Jackson told homicide detectives who wanted to interview his grandson about a deadly daytime shooting that the 22-year-old would give a statement to police the day after the investigation led homicide detectives to the mayor’s home, according to three law enforcement sources.

The officers turned off their body cameras at the mayor’s home and complied with his request, according to the sources. Frank Q. Jackson walked into the police department the next day with his lawyer.

It’s not uncommon for anyone sought for questioning by police to ask for a lawyer before they give a statement. But the sources said not taking that person into custody at that time is an anomaly, especially in a homicide investigation.

In a typical case, the officers would take the person into custody and wait for an attorney to show up before the interview, the sources said. This gives investigators time to collect certain evidence, including gunshot residue tests that would have shown if Frank Q. Jackson fired a gun recently.

Those tests never happened, according to the sources.

Mayor spokesman Dan Williams did not return messages seeking comment, nor respond to a list of questions.

Case Western Reserve University law professor Michael Benza said it’s important in a case to test for gunshot residue as soon as possible. Once a gun is fired, it releases matter from both the front and back of the gun, often getting on the shooters hands and clothing. The test show if someone recently came into contact with a fired gun.

Once hands and clothes are washed, the amount of the matter can be difficult to detect. Police are not required to obtain a special warrant for that type of testing, Benza said.

“You want to do that type of testing as quickly as possible, so you don’t lose that evidence,” Benza said.

Paul Giannelli, a professor emeritus at Case Western Reserve University Law School, said it’s paramount for investigators to swab the hands of a suspect in a shooting as quickly as possible.

“You have to do it quickly,” Giannelli said. “Even putting your hands in and out of your pockets, that gets rid of it. Washing your hands gets rid of it. What you want to have done is to get the residue right then and there.”

Giannelli said officers only needed reasonable suspicion to swab Frank Q. Jackson’s hands. They also could have asked for consent. If he said no, that also could have been documented and used in the case.

“If he refuses you could use that as evidence of a guilty conscience,” Giannelli said. “Then you could say you had reasonable suspicion to take the swabs.”

The officers on Aug. 28 went to the mayor’s home after a 2006 Volkswagen Passat registered to Frank Q. Jackson was spotted speeding from the scene of a fatal daytime shooting that killed 30-year-old Antonio Parra on the city’s West Side.

Officers went to the mayor’s home to interview Frank Q. Jackson. Investigators towed his truck, but did not find the car. Frank Q. Jackson had driven the car as recently as Aug. 13 when he was given a traffic ticket while driving the car, according to court and police records.

The car was found Aug. 30 next to an abandoned building on Holton Avenue near East 93rd Street. Hours earlier, Frank Q. Jackson went to Cleveland police headquarters as promised, defense attorney Sydney Strickland-Saffold said. She said she told her client not to give a statement to police and said he had no knowledge of the shooting.

No arrest or charges have been filed in Parra’s slaying as of Monday afternoon. Cleveland homicide detectives are continuing to investigate the case.

The case isn’t the only recent criminal case involving Frank Q. Jackson that raised questions.

Cuyahoga Metropolitan Housing Authority Police on June 10 investigated an incident in which Jackson was accused of attacking an 18-year-old woman. The woman and two witnesses gave written statements to police.

An officer also noted in his police reports that Jackson returned to the scene in a truck, then sped off when an officer ordered him to pull the truck to the side of the road to be questioned.

Assistant Cleveland Prosecutor Aric Kinast more than a month later decided against pursing criminal charges in that case. Cuyahoga County prosecutors picked up the case and secured an indictment against Frank Q. Jackson on charges of felonious assault, abduction and failing to comply with police.

County prosecutor spokesman Ryan Miday said in a statement that the grand jury reviewed the facts of the case and felt they warranted charges.

Frank Q. Jackson pleaded not guilty Monday to those charges.

Cleveland Prosecutor Karrie Howard on Friday blamed a CMHA detective who he said failed to provide all the evidence to Kinast.

Assistant Cuyahoga County Prosecutor Terese McKenna previously said county prosecutors are able to pursue charges and secure convictions in cases with similar facts, including when a victim later declines to keep participating in the criminal case.