A former Central Intelligence Agency software engineer was convicted by a federal jury on Wednesday of causing the largest theft of classified information in the agency’s history.
The former C.I.A. employee, Joshua Schulte, was arrested after the 2017 disclosure by WikiLeaks of a trove of confidential documents detailing the agency’s secret methods for penetrating the computer networks of foreign governments and terrorists.
The verdict came two years after a previous jury failed to agree on eight of the 10 charges he faced then.
At the earlier trial, Mr. Schulte, 33, was found guilty of contempt of court and of making false statements to the F.B.I. He was convicted on Wednesday on nine counts, which included illegally gathering national defense information and illegally transmitting that information.
Damian Williams, the United States attorney in Manhattan, where the trial was held, hailed the verdict. Mr. Schulte has been convicted of “one of the most brazen and damaging acts of espionage in American history,” Mr. Williams said in a statement.
Those acts, Mr. Williams added, were driven by a grudge against the C.I.A. so strong that it led Mr. Schulte to make “some of our most critical intelligence tools known to the public and, therefore, our adversaries.”
Mr. Schulte, who defended himself at the most recent trial, has argued that he was being made a scapegoat for the C.I.A.’s own failings. Sabrina P. Shroff, a lawyer who represented him at the earlier trial, declined to comment on the verdict on Wednesday.
The investigation that led to Mr. Schulte’s conviction began in March 2017 after WikiLeaks, an anti-secrecy organization, publicly shared thousands of pages of internal C.I.A. materials describing sophisticated software tools and techniques used by the agency to break into smartphones, computers and even Internet-connected televisions.
The document dump — a coup for the group but a serious blow to the C.I.A. — included instructions for compromising various commonly used computer tools, and then using them to spy: the online calling service Skype; Wi-Fi networks; PDF documents; and even commercial antivirus programs of the kind used by millions of people to protect their computers.
The breach, known as the Vault 7 leak, caused “catastrophic” damage to national security, the government said.
Investigators scrambled to find the culprit, and the trail eventually led to Mr. Schulte, a computer engineer for the agency who had helped create hacking tools as a coder at C.I.A. headquarters in Langley, Va.
There, according to the government, Mr. Schulte and his team of elite programmers worked in a secret building protected by armed guards, designing, among other things, malware that targeted the computers of suspected terrorists.
F.BI. agents searched Mr. Schulte’s Manhattan apartment a week after WikiLeaks released the first of the C.I.A. documents, and then prevented him from flying to Mexico on vacation, according to court records and relatives. In June 2018, he was charged with being at the center of the breach.
When it published the information, WikiLeaks said the source hoped to raise “policy questions that need to be debated in public, including whether the C.I.A.’s hacking capabilities exceeded its mandated powers.”
Prosecutors painted Mr. Schulte as less high-minded. They said he was a disgruntled agency employee who had stolen the classified documents as retaliation for what he felt was management’s failure to take his workplace complaints seriously.
“For the C.I.A., it was the ultimate act of betrayal from one of their own,” David W. Denton, Jr., a federal prosecutor, said in the government’s opening statement at Mr. Schulte’s first trial.
That proceeding ended in a hung jury after four weeks of testimony and six days of chaotic deliberations. In the course of them the judge dismissed one juror who violated an order not to research the case, and then shared information about it with the rest of the jury.
The nine counts on which Mr. Schulte was convicted on Wednesday carry a maximum combined sentence of 80 years in prison, a spokesman for the U.S. attorney’s office said. A sentencing date has not been set.
Mr. Schulte still faces a federal trial stemming from what prosecutors say were more than 10,000 images and videos of child pornography that federal agents found on electronic devices in his home in the course of the Vault 7 investigation.
Nicole Hong contributed reporting.