Grigson said Landry has a lower body soft tissue injury and that the team doesn't want to risk aggravating it. The GM declined to be more specific. Landry refused interview requests.
Landry has not participated in the Colts' voluntary offseason conditioning program or any of the club's allotted 10 days of organized team activities.
Grigson echoed coach Chuck Pagano, who said Tuesday that he would have loved to have had Landry involved in the voluntary workouts.
"We can't force guys to do anything," Grigson said. "There are always some guys who like to get away and do things on their own. We knew this when we signed him. We knew this when we signed him because he's always done that through his whole career.
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"It's what we signed up for and what we expected. He was ready last year and came out here and looked as Chris Canty Womens Jersey in shape if not in more shape than anyone, so we expect that this year."
The Colts safety situation is muddled with Landry at one spot but the other up for grabs with eight year regular Antoine Bethea gone to the San Francisco 49ers as a free agent and Corey Lynch on injured reserve with an undisclosed injury.
The candidates to replace Bethea are 11th year veteran Mike Adams, who was signed this week as a free agent, and a pair of reserves, Delano Howell and Sergio Brown, who together have started a total of six NFL games.