WESTMINSTER, Colo.—Police in Colorado are investigating whether a man suspected of fatally shooting his 19-month-old daughter and then wounding himself posted a photo of himself and his daughter to Facebook shortly before the shootings.

Mia McKoy-Phanthavongsa was killed in Monday's shooting at an apartment in the Denver suburb of Westminster, police spokeswoman Cheri Spottke said. The girl's father, Merrick McKoy, was hospitalized. His condition wasn't immediately available.

The girl's mother, Kim Phanthavongsa, called police after an altercation with McKoy, her ex-boyfriend, and told them McCoy was inside her apartment with her child and had a gun, police said.

Officers heard shots when they arrived and found the child and McKoy with gunshot wounds, Spottke said.

Kim Phanthavongsa told police on Wednesday that a photo of the girl and McKoy was taken "near or at the time" of Monday's shootings and that the photo was posted on a Facebook account belonging to McKoy, Spottke said. After the photo was posted, a comment followed that said: "Don't judge me (sic) had no choice." The comments appeared to be from McKoy, but police were still investigating whether he indeed posted it.

Police were working to confirm the mother's statements.

McKoy was the lone suspect in the shootings, Spottke said. There were no arrests by late Wednesday.

Police would not release more details because the shooting remained under investigation, Spottke said.

According to court records, McKoy was under a restraining order barring him from the mother's apartment. He was arrested Sept. 27 on suspicion of burglary, trespassing, assault and making harassing phone calls, the records state, and was released on $20,000 bond.

On June 25, court records show, McKoy filed a lawsuit against Kim Phanthavongsa related to their child, but details weren't available.

Residents of the apartment complex just north of Denver expressed disbelief at the shootings on Wednesday.

The complex is home to relatives and friends of Phanthavongsa, who was from Laos. Several described McKoy as a car enthusiast who sometimes worked on his vehicles at the complex.