The Bears released McDonald on Monday after he was arrested on domestic violence and child endangerment charges in San Jose, Calif. McDonald is accused of physically assaulting the victim while she was holding a baby.
The team signed McDonald this off-season despite several previous incidents, including an earlier domestic violence investigation and a sexual assault investigation.
On Tuesday, McCaskey was asked if he had regrets about signing McDonald.
"I've asked myself that question a lot: What more could I have done? Is there somebody else that we could have consulted with? Should I have taken more time to make a decision?" McCaskey said, according to WGN's Adam Hoge. "I don't know. We thought we had a good structure, a good support system and we thought we had the safeguards in place in case something like this happened."
McCaskey took responsibility for the signing, saying that the safeguards worked effectively, but he "just [needed] to make a better decision."
McCaskey also said he felt sad for McDonald's child and the mother of his child, according to the Chicago Tribune's Brad Biggs.
George: "The overriding emotion for me was sadness. Sadness for the child. Sadness for the mother."— Brad Biggs (@BradBiggs) May 27, 2015
McDonald has played eight NFL seasons, all for the San Francisco 49ers, starting 68 games and recording 210 tackles, 19.5 sacks and three fumble recoveries.
The 49ers released the defensive tackle in December after the San Jose Police Department announced it was investigating McDonald for a potential sexual assault.
- Stanley Kay and Alex Putterman