Whoever's name appears on the title, is the one who needs to sign the title in the idicated spot showing on the above picture. 

I'm the registered owner but I can't find my title:

We can usually still pick up a car even when the title has been lost as long as we can get a signature on some paperwork from the registered owner. Please speak to our towing agent about this when they call you to arrange the pickup. 

The vehicle was abandoned on my property:

We can only pick up an abandoned vehicle if we are able to obtain a signature from the last registered owner.

More Information:

For more on title transferring in Massachusetts, please go here.