Baby Gabriel's grandfather, Frank McQueary, takes witness stand in Elizabeth Johnson trial

PHOENIX - A missing baby's grandfather takes the stand on the third day of the Elizabeth Johnson trial. She's the Tempe mother accused in the disappearance of her son, Gabriel.

Frank McQueary took the stand around 11:25 a.m. McQueary is a retired Phoenix police officer who was aware of the custody dispute between his son and Johnson. This is according to Logan McQueary, the baby's father, who testified Monday.

Logan McQueary said  that his father gave him a voice recorder and he used it to record all conversations between him and Johnson. Logan McQueary told jurors that Johnson said she suffocated Gabriel, stuffed him in a diaper bag, and threw him in the trash.

Logan McQueary told jurors that he and Johnson had an on-again, off-again relationship. They broke up in December 2009 which is the same month Gabriel disappeared, he said.

His former colleagues were also called as witnesses. Cynthia Groulx, a cashier at a retail store where he worked, recalled a time when Johnson went to McQueary's workplace and demanded that he talk to her. Groulx said he locked himself in an employee break room while Johnson repeatedly called his name in a loud voice. Police were called for the disturbance.

Malcolm Phipps, Johnson's former roommate, also testified Monday. Phipps said that Johnson told him she didn't want McQueary to have Gabriel.

The baby went missing in December 2009. Johnson told police she gave Gabriel to strangers at a park in San Antonio, Texas.

Johnson is on trial for kidnapping, child abuse, and custodial interference.