If you trust the data source, you can use eval to convert your string into a dictionary:
eval(your_json_format_string)
Example:
>>> x = "{'a' : 1, 'b' : True, 'c' : 'C'}"
>>> y = eval(x)
>>> print x
{'a' : 1, 'b' : True, 'c' : 'C'}
>>> print y
{'a': 1, 'c': 'C', 'b': True}
>>> print type(x), type(y)
<type 'str'> <type 'dict'>
>>> print y['a'], type(y['a'])
1 <type 'int'>
>>> print y['a'], type(y['b'])
1 <type 'bool'>
>>> print y['a'], type(y['c'])
1 <type 'str'>