<s>
Tumblers	O
have	O
arisen	O
to	O
improve	O
the	O
anonymity	O
of	O
cryptocurrencies	O
,	O
usually	O
bitcoin	B-Protocol
(	O
hence	O
bitcoin	B-Protocol
mixer	O
)	O
,	O
since	O
the	O
digital	O
currencies	O
provide	O
a	O
public	O
ledger	B-Language
of	O
all	O
transactions	O
.	O
</s>
<s>
There	O
has	O
been	O
at	O
least	O
one	O
incident	O
where	O
an	O
exchange	O
has	O
blacklisted	O
"	O
tainted	O
"	O
deposits	O
descending	O
from	O
stolen	O
bitcoins	B-Protocol
.	O
</s>
<s>
Peer-to-peer	O
tumblers	O
act	O
as	O
a	O
place	O
of	O
meeting	O
for	O
bitcoin	B-Protocol
users	O
,	O
instead	O
of	O
taking	O
bitcoins	B-Protocol
for	O
mixing	O
.	O
</s>
<s>
When	O
it	O
is	O
completely	O
formed	O
,	O
the	O
exchange	O
of	O
bitcoins	B-Protocol
between	O
the	O
participants	O
begins	O
.	O
</s>
<s>
Another	O
alternative	O
to	O
mixing	O
services	O
are	O
"	O
privacy	O
wallets	O
"	O
,	O
allowing	O
users	O
to	O
exchange	O
bitcoin	B-Protocol
in	O
an	O
untraceable	O
manner	O
using	O
so-called	O
CoinJoin	O
transactions	O
.	O
</s>
<s>
In	O
December	O
2013	O
cryptocurrency	O
tumbler	O
Bitcoin	B-Protocol
Fog	I-Protocol
was	O
used	O
to	O
launder	O
a	O
part	O
of	O
the	O
96,000	O
BTC	B-Protocol
from	O
the	O
robbery	O
of	O
Sheep	O
Marketplace	O
.	O
</s>
<s>
In	O
February	O
2015	O
,	O
a	O
total	O
of	O
7,170	O
Bitcoin	B-Protocol
was	O
stolen	O
from	O
the	O
Chinese	O
exchange	O
Bter.com	O
and	O
traced	O
back	O
to	O
the	O
same	O
tumbler	O
.	O
</s>
<s>
In	O
April	O
2021	O
,	O
U.S.	O
Federal	O
authorities	O
arrested	O
the	O
founder	O
of	O
Bitcoin	B-Protocol
Fog	I-Protocol
,	O
a	O
Russian-Swedish	O
man	O
named	O
Roman	O
Sterlingov	O
,	O
on	O
charges	O
of	O
money	O
laundering	O
,	O
operating	O
an	O
unlicensed	O
money	O
transmitting	O
business	O
,	O
and	O
money	O
transmission	O
without	O
a	O
license	O
in	O
the	O
District	O
of	O
Columbia	O
.	O
</s>
<s>
It	O
was	O
alleged	O
that	O
during	O
its	O
10	O
years	O
of	O
operation	O
,	O
Bitcoin	B-Protocol
Fog	I-Protocol
laundered	O
over	O
1.2	O
million	O
Bitcoin	B-Protocol
at	O
a	O
value	O
of	O
approximately	O
$335	O
million	O
.	O
</s>
<s>
In	O
2022	O
the	O
tumblers	O
Blender.io	B-Protocol
and	O
Tornado	B-Protocol
Cash	I-Protocol
were	O
both	O
sanctioned	O
by	O
the	O
United	O
States	O
Department	O
of	O
the	O
Treasury	O
,	O
making	O
it	O
illegal	O
for	O
US	O
citizens	O
,	O
residents	O
and	O
companies	O
to	O
use	O
the	O
service	O
.	O
</s>
<s>
In	O
March	O
2023	O
,	O
the	O
tumbler	O
ChipMixer	O
and	O
46	O
million	O
dollars	O
in	O
Bitcoin	B-Protocol
were	O
seized	O
.	O
</s>
