Now a worker in an auto-body shop, Caldwell, 52, said Mr. Kozlow "was someone who basically turned my life around."
Mr. Kozlow, 53, a defender in Philadelphia since 1992, died Wednesday, July 25, of throat cancer at his home in Center City.
The National Association of Federal Defenders gave him one of its three Outstanding Federal Defender of the Year citations for 2010.
Mr. Kozlow, born in Philadelphia, earned a bachelor's degree in 1981 at Hobart College and graduated in 1986 from the New England School of Law in Boston, where he was the lead articles editor for its law review in 1985-86.
Felicia Sarner, now a staff lawyer in the Office of the Federal Defender in Philadelphia and his supervisor for 13 years, said Mr. Kozlow "was one of the most brilliant attorneys I've known."
He "started his career as a prosecutor" in Massachusetts, she said, "and shortly thereafter decided that he wanted to be a criminal defense lawyer, because he wanted to make a real difference in people's lives."
Sarner noted: "It's a reality that in criminal courts anywhere in the country, most cases end up in guilty pleas." For Mr. Kozlow, she said, the question was neither guilt nor innocence, but "ensuring a fair process and treating every client with the utmost respect."
"So he was beloved by his clients and kept in touch with many, long after their cases were over."
Caldwell, identified in Inquirer stories from the 1990s as an FBI informant, said Mr. Kozlow's efforts continued long after the convictions.
"He always took an interest in me," Caldwell said, because "I had kids that I needed to be home with."
Caldwell noted that Mr. Kozlow "was always there for me. He would take you to lunch and sit down and talk. Kept me out of a lot of situations."
The former convict said, "We were supposed to go two weeks ago" to lunch, but Mr. Kozlow was too ill.
Said Sarner: "He had an incredibly strong commitment to social-justice issues and to making sure that poor people received excellent representation in their cases."
Mr. Kozlow's resumé shows that before joining the Office of the Federal Defender, he was an assistant public defender for Philadelphia courts from 1989 to 1992.
While with the federal office, he was also an adjunct law professor at Temple University from 1998 to 2003.
Mr. Kozlow's wife, Maria Maldonado, said his interest in his convicts extended beyond lunches.
"If any of them asked to see him," Maldonado said, "he would always go anywhere, wherever they were housed," in jails and prisons.
In his spare time, she said, his hobby was one that required similar patience and focus.
"He painted miniature soldiers, painted them by hand," Maldonado said. "He and a very large group of friends would meet at conventions" to use their miniatures in historical reenactments.
Besides his wife, Mr. Kozlow is survived by his mother, Doris; grandmother Dorothy; a sister; stepsons Eddie Medina and John Medina; and five step-grandchildren.
A memorial service was set for noon Saturday, Aug. 4, at the Church of the Holy Trinity, 1904 Walnut St.
Contact Walter F. Naedele at 215-854-5607 or firstname.lastname@example.org.