Music by Kevin MacLeod (original composer: unknown). Available under the Creative Commons Attribution 3.0 Unported license. Download link: https://incompetech.com/music/royalty-free/index.html?isrc=USUAN1100296

MacLeod's description:

Genre: Horror
Length: 1:07
Instruments: Glock, Synth

Progressively darker and darker version of "This Old Man". 038
ISRC: US-UAN-11-00296
Unnerving, Eerie 2006