I wanted to accomplish this through a unsecured loan from a friend or family member.

I have underwritten multiple Commercial Real Estate Portfolio loans (in addition to many personal unsecured / secured lines of credit, margin loans and small business loans) ... which has sparked my interest; why not slowly try and jump to the investor side?

It's also amazing how unsecured some of these properties are, we can go look at a property and I'll go into the backyard and my husband jokes that he half expects me to come walking out the front door...unlocked bulkhead doors, windows, back doors, etc.

That would be just as big a mistake on their part as it was for you to lend on an unsecured basis.    

Further, an opened notice from the DMV in this tenant's name related to driving under the influence of alcohol was on the floor, and an unsecured Smith and Wesson handgun was sitting on the bedside table.

Using a credit card may be better in some ways because at least it is unsecured debt. 

If a seller accepts a letter from the bank that the buyer has "over 120K worth of funds available unsecured" then it is a cash dealIf a seller accepts a buyers dad's account image and a letter saying "Junior can buy a house with this if he wants"If a seller accepts "IOU 120K cash at closing" it is a cash offer.The financing contingency falls under how @Mark Gallagher says.Just my 2 cents.

@Juan AlvarezGo out and get an unsecured business line of credit before you need it.

It wrecked me at the time mentally since I'd never so much as paid a late fee on anything the first 35 years of my life, but in hindsight it was smart having that money unsecured. 

Unsecured loans cannot be used for down payments.