That's concerning. She looks down at the building from a few angles, then apparates down near the back door. Another round of divination, this time for humans in view of the door, or bells hooked up to it.

There's a few people milling about inside, but there's no one right by the door. There's electric doorbells on most of the units, but nothing mechanical that'd make a sound if the door opens. 

A quick alohomora to take care of the door lock, a silencer to the hinges, and then she'll step very quickly inside, closing the door behind her.

It's a fairly ordinary looking place, with wooden flooring and eggshell white walls. The entry hall is nestled with a space for shoes and a coat hanger, with a sitting room just past it, and halls leading to a number of bedrooms. 

Carefully, quietly, grateful for her silenced boots, she steps closer to the middle of the house, then casts again. Where in the house are the rifles?

They're in a cabinet in one of the unoccupied bedrooms. 

That's rather more rifles than she'd expect one person to have. Possible suspect?

She heads up to that bedroom, steps in, closes the door, and then casts a tracking spell, carefully containing the generated vestiges to just the room she's in. Who's been fiddling with that cabinet?

Looks like just the person who's been using the room. 

Tch. Any sign of information about Dr. King's schedule or movements in here? She makes sure to carefully levitate things out of the way, to avoid leaving prints in the room, and then put everything back exactly where she finds it.

There's nothing incriminating at a look around - just the guns, stored in cases, with the ammunition set aside in a different area. 

No certainty, no clear indications.

She'll just have to take precautions.

This'll be fiddly, but she delicately casts an alarm paling (like a ward but smaller and temporary) on the cabinet, set to give her a distinctive mental nudge if anyone opens it.

She lets out a breath at the rush of magic it takes, the delicate focus a bit mentally tiring.

Worth it, though. She can come back here in a trice if this boarder turns out to be the shooter.

A quick silencing charm to the room — underpowered so it'll fade in a few minutes — and then she apparates to the motel parking lot to look for the hunting rifle she sensed.

It's in the back of a Ford Thunderbird, it looks like. 

That'll need another alarm paling. And then she's popping back to her motel room to grab her thermos, fill it with water, grab some ice from the ice machine at the end of the hall, and lean against the wall outside Dr. King's door under a fresh disillusionment and a supersensory charm to increase her field of view, enhance her senses, and provide additional angles of perception. 

Stakeout time. Anyone points a gun in this direction, she'll see it. Anyone touches one of those alarmed guns, she'll know.