Washington said that Myanmar's quasi-civilian government, which replaced junta rule four years ago, had "informed us that they are looking into the case".
"We call on authorities to investigate this crime and bring the perpetrators to justice in a credible and transparent manner," said State Department spokeswoman Jen Psaki in a briefing on Wednesday.
The battered bodies of the two women, aged 20 and 21, were found on January 19 in a remote village in Shan state where they were teaching children on behalf of the Kachin Baptist Convention, according to KBC spokesman Lama Yaw.
“We went there as soon as we heard the news. They lived alone in the church compound. When the authorities found them, they were attacked with knives and their heads bashed with wooden sticks. They were completely naked,” said Zaw Ya, secretary of KBC’s Mong Kong zone.
Images of the women's injured corpses have been widely circulated on social media, stirring outrage in Shan and neighbouring Kachin state, which have been wracked by conflict between Myanmar's army and ethnic minority rebels in recent years.
"The victims are dead and can't point out who did it to them. But everyone in Myanmar - not only the Kachin people - knows the truth," Lama Yaw said, referring to KBC claims that soldiers were responsible.
Local residents said that the accident happened when soldiers from the No. 503 Infantry Regiment under North-East Command entered Kaungkhar village where the teachers stayed.
“Locals said there were other government troops coming and going during the fighting but nothing happened. The rape and murder happened when the No.503 Infantry Regiment arrived,” said Zaw Ya.
A senior officer from North-East Command confirmed the news and said they are still investigating.
“We don’t know exactly what happened. It is a coincidence that the incident happened while the army is near the area. Some assumed that it was done by the army. Nobody can tell exactly. It is under investigation now,” said the senior officer to the Daily Eleven.
The KBC called for fair judgement while the government and local organisations are cooperating with Muse district police force to investigate the incident.
“We will know the answer tomorrow or the day after tomorrow. I think the authorities will announce it,” the officer said.
A delegation led by Dr Alan Sam Sung, secretary of Myitkyina based KBC went to Kaungkhar village. The authorities conducted a post-mortem on January 20.
Although the government troops often passed through Kaungkhar village, it is the first brutal crime that happened in the village.
Myanmar has been wracked by sporadic civil wars across its ethnic minority borderlands for more than half a century, leaving a legacy of entrenched mistrust of the army, which has been accused of committing serious abuses with impunity.
The government has put a national ceasefire deal at the heart of reforms, but heavy fighting in Kachin has overshadowed peace talks.
The international community has also raised rising alarm that the country is backsliding in other key areas of its democratic transition.
Lama Yaw said he was travelling with a procession carrying the coffins of the two women to the Kachin state capital Myitkyina, where their parents were waiting to hold funerals.
He said they had been greeted by large crowds on the two-day journey.
"Even in the freezing weather, people were waiting for us," he said.
Fighting between the Myanmar military and Kachin Independence Army (KIA), which reignited in 2011 after the collapse of a 17-year ceasefire, has displaced around 100,000 people.
Last year the military admitted that its troops had shot a freelance journalist known as Par Gyi who was in custody at the time, but said that he was working for an armed group in southern Mon state - a claim his family denies.