The remains of 30-year-old Jana Armstrong were found in bushland late on Saturday, four days after she vanished from Toowoomba, west of Brisbane.
Hours after the grim discovery, police arrested her 48-year-old former partner and he was later charged with domestic violence-related murder.
Ms Armstrong's body was found in rough and steep terrain near a national park at Esk, northeast of Toowoomba, by two members of the public who were out hunting at night, police said.
While the remains were yet to be formally identified, investigators said they were certainly those of the young woman, who gave birth to a baby boy earlier in the year.
Detective Acting Inspector Brian Collins said police were still investigating the possibility the accused killer had moved Ms Armstrong's body in the period after she disappeared.
"This is a horrific crime," he told reporters on Sunday.
"People in the community would be horrified that a young lady, a 30-year-old with a four-month-old child, has had her life taken."
A post-mortem examination was yet to be carried out and police had not confirmed the cause of death or whether a weapon was involved, Det Insp Collins said.
No relevant domestic violence protection order was in place in the relationship, he said, although all interactions with police before the death would be examined.
"I don't think there's anything police could have done to prevent this at all," Det Insp Collins said.
In a tribute to her sister, Faith Isaacs vowed to take care of her young nephew following her sibling's death.
"Losing my beautiful sister in this way is something I will never be able to understand or put into words," she posted on social media on Sunday morning.
"I promise you, Jana, your beautiful baby boy will always know exactly who his mummy was."
Previously released footage of Ms Armstrong from the day of her disappearance showed her carrying her four-month-old baby and pushing him in a pram across a car park.
Police continue to appeal to the public for any relevant information, CCTV or dashcam footage that could aid their investigations.
They have been trying to trace the movements of Ms Armstrong and her white Hyundai Kona in the hours after she was last seen.
Investigators are particularly interested in any footage from between Toowoomba and Esk, along Esk Hampton Road and the New England Highway, between 10.30pm on July 7 and 1.30am on July 8.
The 48-year-old man is due to appear in court on Monday.
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