Then found out the guy just got out of prison for sexual assault.

I worked with sexual assault cases; others worked homicide cases. 

Doug was at the party, is Tiffany's bestie, sexual relationship unclear but quite probable.The party happened in the downstairs duplex apartment.

We qualify tenants using Resident Research and we screen for the following: - 600 + credit score- No sexual, drug or violent related crimes - No previous evictions - 2.5 to 3x income to rent ratio, verify with paystubs- Like to see a minimum 1 year job history, verify with paystubs - Call previous landlord (if applicable) for reference I'd do some online research for local companies who do the following:  HVAC, plumbing, electrical and general handyman. 

Meaning you cannot refuse to rent someone based on Race/Ethnicity, Age, Family size, Gender, Sexual Orientation, or Marital Status.

It's not on my application, but I also don't accept anyone with recent criminal charges, any violent/sexual offenses, or any evictions.

However, the owner cannot make oral or written statements, or use notices or advertisements which indicate any preference, limitation, or discrimination based on race, color, religion, sex, sexual orientation, marital status, national origin, ancestry, familial status, source of income, or disability.47 Further, the owner cannot discriminate on the basis of medical condition or age.48 A person in a single-family dwelling who advertises for a roommate may express a preference on the basis of gender, if living areas (such as the kitchen, living room, or bathroom) will be shared by the roommate."

Thats what kind of what Ive been thinking about as well.She does not look like a sexual offender or a robber either... 

If we want to show the unit to as many potential applicants as possible we only put it as the first page of the application, otherwise it is good to put in the ad.We cater to a low income crowd and do not charge for screening, so we keep the criteria pretty vague:Our Criteria:We do not deny housing for race, color, religion, sex, national origin, handicap, sexual orientation, marital status, or familial status.We do deny housing to individuals:when the application is not complete or accuratewhere there is not sufficient income/resources to pay rent and livewhere there is poor prior tenancy: evictions, violations, damage to rental property, poorly handled move outs, amounts are still owing to landlords or utilities.

He also noticed sexual deviants housing is a goldmine waiting to be tapped (pardon the pun)....