Joshua Adam Schulte allegedly stole classified information relating to national security from the CIA to be transmitted to Wikileaks.
FBI agents discovered alleged child porn in Mr Schulte’s apartment after his arrest.
Mr Schulte faces 13 separate charges and could face up to 135 years in prison if found guilty.
Using information allegedly provided by Mr Schulte, Wikileaks published thousands of documents in March 2017 detailing the CIA’s cyber-warfare programme.
Mr Schulte designed malware used to break into terrorism suspects’ and other targets’ computers for the CIA for six years. He quit the spy agency in 2016 to work in the private sector.
Codenamed Vault 7, the 2017 breach told how the CIA can take over iPhones through malware and turn smart TVs into surveillance devices.
It is believed to be the agency’s largest leak of classified documents.
“Schulte utterly betrayed this nation and downright violated his victims. As an employee of the CIA, Schulte took an oath to protect this country, but he blatantly endangered it by the transmission of Classified Information.” FBI official William Sweeney Jr. said in a statement.
Wikileaks shared a statement from Mr Schulte regarding his arrest by the FBI, in which the software engineer said “the agents lead [him] around like a prized dog”.