Connect SFDC lead/contact to Anonymous Marketo lead

[Anonymous]

We just received a phone call from a prospect stating they were on our website and would like more information. Based on Marketo and another web analytics tool matching the caller ID, I can identify the anonymous user session in Marketo. How can I connect the known SFDC lead to the anonymous marketo lead?

Is this possible?

[Anonymous]

The anonymous leads are converted to known and can be synchronised to SFDC when they click a tracked link in emails or fill out a form.

If i am following you correctly you can find the anonymous record and respective activity log. Filling out the email adress manually and sending a welcome email with tracked link would be the quickest and simplest method to convert it. You can then select that lead and run a single flow action Sync Lead to SFDC.