The federal investigation into the death of convicted sex-trafficker Jeffrey Epstein was marred by significant lapses, experts told CBS News, including the failure by investigators to interview potential witnesses, properly preserve certain evidence and run basic forensic tests. Nearly two years passed before investigators interviewed the two key corrections officers on duty the night Epstein died. And details pulled from 90 photos of the cell and other evidence collected in the hours after Epstein's death but before FBI agents arrived to process the scene " appear to show a succession of basic oversights, ranging from an absence of evidence markers to items being moved, experts told CBS News. "The FBI literally has all of the best tools. I mean, spared no expense. They have every tool you can imagine. And they used none of it as far as we can tell," forensic analyst Nick Barreiro said after reviewing the photos. "I do not believe he died by suicide, no," Epstein's co-defendant, Ghislaine Maxwell, said this summer during her interview in August with the Deputy U.S. Attorney General Todd Blanche. Epstein's body was discovered at 6:30 a.m. on Aug. 10, 2019. The first FBI agents arrived at the cell more than seven hours later. When they arrived, photos show they found a disorganized, rifled-through clutter. Epstein's lifeless body had already been removed from the cell, eliminating a critical source of information investigators would need to determine how and when he died.