Prosecutors used baby Gabriel's mother's own words against her during trial on Monday.
The emails show McQueary wrote Johnson that he loved his son and wanted to be apart of his life, but he said Johnson kept pushing him away.
Johnson is on trial for kidnapping and custodial interference charges.
Jurors also heard a recorded phone call Johnson made from jail after she was arrested in Miami in December of 2009.
During the call, Johnson told friends, family, and a TV reporter she gave her son away to a couple she met at a San Antonio park even though she knew nothing about them, not even their last name.
The state is expected to wrap up its case on Tuesday.