The Assam-based 'tantrik' Luman Haqib had fled the country taking advantage of the porous Indo-Bangladesh border in Assam's Dhubri district late last month, they said.
"We lost him," Inspector General of Police (Western Range) GHP Raju told agency, adding that "It is a matter of time that Haqib will be brought to trial."
"We are following up with the Court exploring all possible legal options to get him to trial sooner or later," he said.
Armed with a non-bailable warrant against him, the Meghalaya police are resorting to "all possible legal options" to bring him back, he said.
Haqib was arrested by the Assam police on October nine, three days after the death of a seven year old boy at Tura but was released on surety at Mancachar police station.
Havildar Chandrawan and constable Babu Khan of the BSF have been released on bail last week in connection with the case.
The body of a seven year old Krishna Singh was recovered from near the BSF 121 battalion headquarters at Tura on October 6.
Post mortem report pointed to multiple injuries, including that of incense sticks, pierce wounds and others.