Music by Kevin MacLeod. Available under the Creative Commons Attribution 3.0 Unported license. Download link: https://incompetech.com/music/royalty-free/index.html?isrc=USUAN1100813

MacLeod's description:

Genre: Horror
Length: 2:08
Instruments: Basses, Cellos, Violins, Percussion
Tempo: 100

Mournful piece with a nice melody. Melody starts at 40 seconds in. Feel free to chop out as much opening as is required. The low beat is a bass drum with the attacks cut off.
ISRC: US-UAN-11-00813
Dark, Intense, Mysterious, Suspenseful 2011