Last year which killed five relatives -- such as two young kids -- by the West African state of Senegal, according to government.
The fire erupted in the town's Green Valley Ranch area on Aug. 5, murdering Djibril Diol, his spouse Adja, along with their 2-year-old daughter Kadida. His sister Hassan Diol along with her baby daughter, Hawa Beye, also expired.
Authorities said three others escaped by jumping from an upstairs window.
"Our homicide group, together with our partners in the ATF, U.S. Secret Service, along with the Denver Fire Department, worked tirelessly to identify people responsible for this dreadful crime, and we invite those who encouraged the household members and the Senegalese community," said Denver Police Chief Paul M. Pazen.
The fire ravaged Colorado's Senegalese community. Some feared that the family might have been targeted because they were Muslim immigrants in the West African country, reports stated.
Authorities on Wednesday said researchers haven't discovered any evidence to indicate the crime was motivated by prejudice.
Authorities declared a 14,000 reward for information resulting in an arrest in a news conference last August that contained Senegal's representative to the United Nations.
"I need people to research their hearts... and comprehend this was a household that has been flourishing. They were going [in] the ideal direction."