Well they are taking there time.
Police said the suspect was one of 600 people that detectives on the inquiry, known as Operation Grange, originally looked at, though he had not been a suspect.
After an appeal in 2017, "significant" fresh information about him was provided.
Since then, Met detectives have carried out "extensive inquiries" in Portugal and Germany in order to gather more details about him.
Scotland Yard said they were trying to "prove or disprove" his involvement in the case and retained an "open mind".
According to an article I read last night (will add link, and it may not be accurate anyway), there had been a tip-off about him back in 2013 after an appeal on the same German "Crimewatcher"-style programme back then, but there wasn't enough to make a charge.
I wonder if that was what the dig was about back in whenever (2014?) ?
Then, in 2017, another tip-off flagged the same person, with what I gathered was further information.