Over the last two years, the news media and Congress have brought attention to many deaths in the immigration detention system that appear to have involved substandard medical care or abuse. But a trove of documents obtained over recent months by The New York Times and the American Civil Liberties Union sheds light on even more fatalities.

Among the most haunting cases to emerge from the files are deaths that were undisclosed at the time but foreshadow the later fatalities that galvanized public attention.

One example is the case of Miguel J. Rodriguez Gonzales, 43, a longtime legal resident of California who was detained for immigration violations on Feb. 22, 2006. He had end-stage renal disease, diabetes and chronic heart failure, and was receiving dialysis at a hospital three times a week.

Records show that Mr. Rodriguez fell at least five times during his first 10 days in detention and reported “intense pain all over.” By March he was unable to shower by himself, and “for hygiene issues” he was sent to a disciplinary isolation cell. Soon he had to be taken to the clinic in a wheelchair because he was unable to walk.