So, guy above is not really correct here.
Being is a present participle. It's often wrong when people try to use it instead of a simple active verb: "I am being a doctor" vs. just "I am a doctor."
It does not make a sentence passive. You can say "The crime scene is tested by the forensic experts," and that's still passive. That's usually better than employing the participle there, "The crime scene is being tested."
The only time you should use the participle is to emphasize an ongoing action, like "Right now, the crime scene is being tested by the experts. Later, it will be cleaned up."
Like any participle, it can also be a gerund in a modifying phrase, and that's fine as well. "Being a doctor, he knows a lot about anatomy." Just make sure you're actually intending to create a modifying phrase (i.e. it's not necessary to the meaning of the sentence), and that it's clear what exactly it's modifying.