Yes, refugees can easily be criminals or terrorists for the very same reasons we have all the sympathies for them (They are homeless,Countryless,shelterless,hungry,lost loved ones etc all are genuinely sad and true reasons).Don’t get me wrong I am not against open borders and accommodating refugees,I am merely pointing towards the potential reasons that can lead to such atrocities like Paris .A common homeless,jobless needy person is the most easy target for the ISIS recruiters.So how a refugee can be enticed to become a terrorist the main four factors are
>Brainwashed .They are brainwashed that their sufferings produced and orchestrated by the countries they wish to take refuge in (not completely false but overly exaggerated ).In their deeply hurt state of mind while they have lost their loved ones,their children ,their homes ,their settled lives they can easily be persuaded.
> Desperation. As a desperate and needy person he needs to safeguard his live as well as his immediate family,an offer from ISIS to help him reach any country in Europe as well as food,money and protection is more than enough for him to feeling warm and good about them.
>Trapped .All of them are not going to enjoying what ISIS tends to do.So few of them would be hesitant and apologetic but they are trapped in a massive and hideous web,they can’t escape until they die for the cause or get lucky.
>Believers .Yes a very few number of refugees would be the die hard followers of ISIS.They would jump on any opportunity to become a refugee ,escape from their hell situation in their home country and flee towards the Jannah (False concept according to Islam)of their enemy’s country.