PITTSBURGH (KDKA) — Fifteen-month-old Marcus White, Jr. was shot and killed while he was at a picnic with his family in Pittsburgh’s East Hills neighborhood in 2013.

Investigators found that an aunt of “Baby Marcus” tried to shield him while the gunfire erupted.

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(Image Provided By Family)

The case has been active for nearly a decade, but a suspect is behind bars in a new development.

Twenty-two-year-old Gregory Parker was taken into custody on Saturday afternoon and is accused of having pulled the trigger.

Photo Credit: Pittsburgh Police

Paul Jubas, attorney for the family of “Baby Marcus” called the arrest bittersweet.

Jubas said that on one hand, they are another step closer to justice for “Baby Marcus,” but on the other hand, they’re upset that it took over seven years to reach this point.

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Parker is facing criminal homicide, criminal conspiracy, aggravated assault, and gun charges.

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Parker was taken to Police Headquarters on Saturday before being transported to the Allegheny County Jail.

KDKA spoke with Jubas on the steps of the City-County Building on Saturday.

Jubas claims that police had a confession years ago from Parker, and alleges that police avoided making an arrest to use Parker for information on another case.

Now Jubas is asking Allegheny County District Attorney Stephen Zappala to step away from this case.

“He decided to trade somebody who confessed to murdering a baby so that he could get a conviction of two innocent defendants and it’s entirely unacceptable,” Jubas said.

“We will not accept this individual being in charge of the prosecution of Marcus’ killer going forward,” said Jubas.

Jubas also said that he will be filing a lawsuit on Monday against Zappala’s office, Allegheny County Police, and the United States for an Alcohol, Tobacco, and Firearms agent’s role in the investigation.

Police have not said what evidence was used to make the arrest or why the arrest happened on Saturday.

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Police have also not said whether or not they received a confession as “Baby Marcus'” family alleges.