An Army official desribed the hour-long service, which was closed to the public, as "very emotional."
Ivins' co-workers who spoke at the service described him as a "brilliant scientist" and "a mentor" who was admired for his intellect and for his "quirky sense of humor," the Army official said.
The court documents released today painted a much darker portrait of Ivins.
One affidavit, from a postal inspector, said that Ivins, a 62-year-old anthrax researcher, was suffering from serious mental health problems in the months before the attack and told a co-worker he had "incredible paranoid, delusional thoughts at times" and feared that he might not be able to control his behavior.
Ivins died last week of a drug overdose as prosecutors were preparing to charge him with murder in connection with the anthrax letters. His lawyer has said that Ivins would have been found not guilty had he lived.
Federal law enforcement sources said the FBI is ready to close its multimillion dollar investigation into the 2001 anthrax mailings.
The release of the documents came hours after authorities briefed the victims of the attacks.
The government's investigation traced the anthrax sent in 2001 to members of the news media and government officials, to the same batch of that strain of the deadly virus. The affidavits say Ivins was the sole custodian of that batch, though those close to him have said that as many as 30 other scientists may have had access to it.
In the days before the two batches of letters were sent, Ivins reportedly spent an unusual amount of time in the lab after hours, on a few occasions staying past midnight, the affidavit says.
When asked in 2005 why he was spending so much time in the lab, Ivins reportedly told investigators that "home was not good" and that he went to the lab to escape.
Asked for samples of the anthrax from his lab, Ivins apparently attempted to mislead investigators, the affidavit claims, by providing the wrong samples.
The documents are the latest twist in a seven-year-long investigation that has drawn criticism of the FBI, which focused for a time on the wrong man.
The government recently agreed to pay nearly $6 million to Steven Hatfill, a former Fort Detrick researcher, who was named a "person of interest" in the case.
When the Justice Department made the announcement that effectively exonerated Hatfill, investigators waited for Ivins to react.
Weeks later, Ivins allegedly began making threats during a therapy session. Jean Duley, who had been Ivins' social worker in therapy sessions, was convinced he might try to kill her and others.
She recently went to court seeking protection from Ivins. During a hearing on the matter, she described a chilling July 9 group counseling session. "He was extremely agitated, out of control," she said.
The evidence against Ivins likely will never be tested at a trial and some have been skeptical of the FBI's case, particularly in light of the government's focus on Hatfill, who was never charged.
The FBI used new DNA forensic techniques to link the anthrax spores used in the attack to the flask Ivins reportedly controlled. But that new technology has never been used -- or tested -- in a court of law.
So far, the FBI has not firmly placed Ivins at the sites where the anthrax letters were mailed, which include Princeton, N.J.
ABC News' Luis Martinez contributed to this report.