A judge spared an 85-year-old former US Army engineer any prison time for passing secret documents to the Israelis in the 1980s but said it remains a mystery why such a grave assault on national security took 23 years to prosecute. US District Judge William H. Pauley III on Friday scolded Ben-ami Kadish for letting the Israelis steal classified documents between 1979 and 1985 from the Armament Research, Development and Engineering Center at the Picatinny Arsenal in Dover, New Jersey, where he worked. "What you did was a very grave offense," the judge told Kadish, who hobbled to a lectern with a metal cane to deliver a short statement before he was fined $50,000 but was given no jail time and no period of probation. Kadish, who seemed to fall asleep while his lawyer argued for leniency, apologized. "It was a mistake. It was a misjudgment," he said. "I thought I was helping the state of Israel without harming the United States." The judge told him that it was difficult to dismiss his conduct as a simple error in judgment but that it would serve no purpose to send him to prison since he was so old and in poor health and because the government had drastically reduced the seriousness of the charges. "This was not one mistake," the judge said. "This was over many years." The judge questioned why it took until 2008 to charge Kadish. Prosecutors said it took the FBI until then to assemble enough evidence. In December, Kadish admitted passing the documents to the Israelis by letting Yossi Yagur, an Israeli government agent who had requested them, photograph them in the basement of his home. He pleaded guilty to a count of conspiracy. The judge called Kadish's crime "stealthy and sustained" and noted that Kadish remained friends with Yagur for decades, even visiting him in Israel in 2004. He questioned how Kadish earned more than $100,000 in 2007 even though he hasn't had a job in years. Kadish's lawyer, Jack T. Litman, said his client had nearly $1 million in securities that generated substantial revenue. When the $50,000 fine was ordered, Kadish said, "No problem." After his lawyer asked the government to return his passport, Kadish pressed him to also ask prosecutors to return stamps he had received from Yagur but that were seized by investigators. Kadish was born in the United States but was raised in what was then Palestine from age 4 on a farm in an area the British government was trying to turn into a Jewish state. He fought in the British and US armies in World War II. The government has said he let Yagur photograph documents about nuclear weapons, a modified version of an F-15 fighter jet and the US Patriot missile air defense system.