Updated 8:30 p.m. Sunday to reflect that Guyger has been arrested.

The investigation of Dallas police officer Amber Guyger's killing of 26-year-old Botham Jean is likely to take longer and be less transparent now that it’s in the hands of the Texas Rangers.

Police Chief U. Renee Hall said Friday that the Texas Rangers had been called in to help. By Saturday, Dallas police had completely handed over the case to the Rangers.

The decision to relinquish the investigation is a rare one, defense attorney and former prosecutor Toby Shook said. The Dallas Police Department typically investigates shootings that involve its own officers.

Shook worked closely with the Texas Rangers when he was a special prosecutor in the case of the 2013 murders of the Kaufman County district attorney, his wife and a top prosecutor.

Smaller agencies often call on the Rangers to investigate police shootings because the division of the Texas Department of Public Safety has more resources, he said.

“That's not what we have here with Dallas,” Shook said.

The fundamentals of conducting the investigation won’t change much, he said. But the process is likely to be slower and there probably won't be as much information made available to the public.

“The Rangers can take longer, and the Rangers are traditionally pretty tight-lipped,” he said.

So far, the Rangers haven't had much to say about the investigation, despite public pressure for answers to key questions.

A spokesman has declined to explain why the agency asked Dallas police to hold off on obtaining an arrest warrant.

The Rangers also haven't provided insight into the moments before Guyger opened fire that could help explain how the off-duty officer may have entered Jean's apartment at the South Side Flats in the Cedars.

At the same time, the Texas Rangers are refusing to provide information about the next step in their investigation. Dallas police are referring all questions about the status of the case to the state agency.

Guyger was arrested Sunday evening and booked into the Kaufman County Jail on a manslaughter charge. That was more than two days after the 10 p.m. Thursday shooting.

The police chief had said Friday that the department had initially intended to charge her with manslaughter. But on Saturday she said the Rangers had learned new information and wanted to investigate further before a warrant is issued.

Chief Hall and the Texas Rangers have disclosed nothing about the new information the Rangers have discovered.