"It's a complex investigation by any measure and it spans a number of years – the investigations team has already hit the ground running," Kaldas told Radio National.
The Met police said: "The death of Essayas Kassahun was a tragedy and what followed was a complex investigation for which one person remains convicted.
"This was a complex investigation involving many different parties and one that we worked on in cooperation with the Crown Prosecution Service.
DCI Karen Mizzi said: "This is a complex investigation into numerous allegations of sexual abuse and assault dating back over several decades.
He said: "We are still at the very early stages of what is a complex investigation and we have dedicated officers working to establish the full facts.
The IPCC said: "This is a complex investigation that involves gathering information including witness statements, pathology, forensics and ballistics analysis and we have stated to the coroner that it will be completed within four to six months," the statement said.
Met police detective inspector James Hale said: "This was a complex investigation targeting criminals both inside and outside of prison as part of the Met's fight against gang and gun crime.
Thereby, the goal of this work is a complex investigation of structure and property relaxation behavior in welded joints of dissimilar types of polyethylene, using the methods of wide- and small-angle X-ray scattering, differential scanning calorimetry, and thermal analysis.
Speaking in court, Detective Sergeant Harry Rai, who led the case, said: "This was a complex investigation into a criminal syndicate who used various methods to distribute high purity cocaine around the country and into Derbyshire.
There, the remains will be examined by experts - part of what is expected to be a complex and lengthy investigation.
