Hmm I thought it was possible since this is how Bitcoin came about. Anonymous transactions. I know for sure most Japanese gangs still uses Bitcoin because of this. Using proxy in a public network can definitely hide your identity no?
You can hide your identity, but if the police want to find out who used a particular wallet, then the proxy and VPN will not help you here, since any VPN service is required to provide data on which IP requested the proxy service at a certain time in a certain place. Then you will be found by geolocation.