"Investigators have explored the contents in social media," a spokesman of the Indonesian Police Inspector General Boy Rafli Amar stated here, Tuesday.
The case has emerged following the polices investigation on social media since December 2016.
Preliminary investigation revealed that Bambang had sold the book directly, using his Facebook account to promote it.
"Bambang Tris Facebook account has been used as a media for marketing," he said, adding that the police had detained Tri earlier at the weekend.
The book was allegedly written without any supporting references.
"The suspect did not have any documents that link to his allegations that Jokowi has falsified his data for presidential candidacy to the KPU (General Election Commission)," a spokesman of the Indonesian Police Brig. Gen. Rikwanto remarked.
The spokesman added that the suspect had allegedly spread hatred through the publication.
Rikwanto stated that everything written in "Jokowi Undercover" is based on his personal opinion, while his photometrical analysis was based on his personal perception and assumption, without any expertise.
"The motive of the suspect is based on his intention to make the book more interesting and to draw public attention," he pointed out.
According to Rikwanto, the suspect has spread hatred against children of the members of the Indonesian Communist Party (PKI), which was disbanded in 1966.
The suspect has also spread hatred against the press, as he stated in his book that the victory of Jokowi and Jusuf Kalla was owing to the success of the mass media in disseminating public lies.
"In page 140, he wrote that the Giriroto Village in Ngemplak, Boyolali Regency, was the stronghold of the PKI, while the party was disbanded in 1966," Rikwanto said.
The police have questioned some witnesses, including two personnel of the Central Java Police, experts in the field of information and technology, linguistics, history, and sociology.
The police have seized computers, cellular phones, flash drives, a book titled "Jokowi Undercover", and a document of President Jokowi as the presidential candidate in 2014 obtained from the KPU and Jakarta General Elections Commission in Jakarta and Surakarta.
Bambang has been held at the Jakarta Police detention center for further investigation.
He is charged with Article 45 of Law 19 of 2016 of law on electronic information and transaction for inciting hatred against a certain group and Article 207 of the criminal code for insulting government officials or a public institution in Indonesia.
(Reported by Anita Permata Dewi/Uu.S022/INE/KR-BSR/A014)