"She is the last girl I will ever love," Sullivan said Saturday.
Sullivan was unsure whether Veronica's mom, Ashley Moser, was aware of the death of the daughter they shared on Friday.
A close family friend told 9NEWS that Ashley was told of her daughter's death on Saturday.
On Friday, Ashley Moser drifted in and out of consciousness in the ICU, bullets lodged in her throat and abdomen. In her waking moments, she called for her 6-year-old daughter Veronica.
Nobody had the heart to tell her that Veronica was already dead, the youngest victim killed at a Colorado movie theater in one of the worst mass shootings in U.S. history.
"Nobody can tell her about it," Annie Dalton said of her niece, Ashley Moser. "She is in critical condition, but all she's asking about is her daughter."
Veronica just started swimming lessons on Tuesday, Dalton said.
"She was excited about life as she should be. She's a 6-year-old girl," her great-aunt said.
The young girl was among the 12 people killed when a gunman barged into a crowded Colorado theater, set off gas canisters and opened fire as spectators dove for cover. Dozens of others were injured, including the 25-year-old Ashley Moser and 10 others in critical condition as of Friday night.
To donate to the Moser family, go to any Wells Fargo Bank and request the "Donation Account for Ashley and Veronica Moser". A family spokesperson says this is the only official donation account for the family.
(KUSA-TV © 2012 Multimedia Holdings Corporation with The Associated Press)