Reverse Engineering Bessel LPF (sample frequency needed)
I don't think Deve's answer is correct. The coefficient determine the transfer function in normalized frequency. You can determine at what relative frequency the transfer function hits -3dB. Let's say it's 0.01. Since you  know this is corresponds to 10 Hz you can infer that the sample rate is indeed 1000Hz. 
This code is difficult to read and there isn't a single line of comment in it, nor is there any explanation of what the state variables so it's difficult exactly which number is what coefficient (b0,b1,b2, a0,a1, a2 etc) but it is in principle possible to infer the sample rate.