Check before create contact

Content

Hi All,

I need to check whether the given email id have contact or not. if the mentioned email id has contact, i need to create incident for that contact. if the email id not having contact then create a contact as well as incident for that contact.

Example:

Its like a enquiry page. First user enter their information like first name,last name and email address then they will give interested product details through opa interview. if that particular email id has contact then incident should create under that email id.(only incident). if given email id not having contact then contact as well incident should be create (contact + incident). i need to check contact before creating incident.