Chief Prosecutor Gunnar Fjaestad hopes to begin court proceedings by February next year at the latest.
The man who carried out the original theft worked at the royal library. He was interviewed by police and released pending further inquiries. However, the 48 year old was later killed in a gas explosion at his flat in Stockholm in December last year.
In connection with the latest arrest in Germany, police have recovered a number of valuable books but many are still missing. Stockholm’s university library has six books unaccounted for, two from the early 15th century and four from the 17th century.