Even when hiring through an agency, how do you guard against a home care person being a snoop or a thief? Screening can miss things.

You can place security cameras throughout your house if you're not trusting those you hire. You can find some fairly inexpensive ones now by Blink, Ring, and the like.
I used the Blink cameras when my husband was bedridden in our living room, so I could check on him from my bedroom without getting out of bed, and also when I had to be out and about for any reason, so I could check on him to make sure he was ok. They now make them with 2 way talk as well.

One of the caregivers I hired DID pass background checks.
I sure wish I had cameras. Would have made it easier when I went to the police station to report suspected theft.
I gave the officer all the info I had, he did a quick check and returned to my house less than an hour later with a STACK of papers showing stolen items that she sold at a pawn shop.
This did not include food, toilet paper and other goods she stole nor property damage!
Sad fact is a background check will show convictions only.
Install cameras.
cameras are legal without permission. Audio needs consent. Cameras can not be placed in areas where a person would expect privacy. So no bathroom. If this is a live in there private room can not have a camera. But a camera can be placed in the bedroom of the person the caregiver is caring for.
Get a safe place all private, important papers should be in a safe. When in doubt, put it in the safe

You can guard against thieving and snooping by taking basic security measures in the home.
Lock up valuables (jewelry, checkbooks, credit cards, ATM, cards).
Lock up personal things that you don't want a stranger looking at.
This is how you guard against thieving and snooping.
As for unacceptable behavior and poor attitudes. If the hired caregiver isn't a good fit with the person they're hired to take care of, it's the responsibility of the agency they work for to replace them with a different one. This is why the pay to an agency caregiver is so lowly. The agency who employs them normally takes half or more of that's collected for the service. The agency is management. Their job is supervising, making sure the worker is properly doing their job, and making sure the client has coverage if the regular caregiver can't be there.
If you're worried about bad attitudes and behavior, hire a private-pay caregiver not employed by an agency. Bad attitudes and behavior are pretty rare among well-paid caregivers who work for themselves and don't have an agency exploiting their labor and wages.
You still have to keep an eye on anyone you hire because they're a stranger. After a while when they've proved themselves, it can be more relaxed.

A wireless camera! I pointed mine towards outside doors that gave a wide scope of the inside of the house along with it & had sound. I checked in from time to time & had to fire health aids or have talks with them. One health aide drowned out my mom by turning music up extremely loud, she was fired. Another started purposefully getting in my mom’s space & holding her phone camera to her face to record her reaction, she was fired. Others were just rude. Nobody is perfect & it’s a hard job but your loved one deserves to be treated kindly. They deserve tranquility. They’re dealing with enough in their minds without a cruel caregiver. I always told the caregiver during interviews that there’s a security camera pointed at the door (of course it was 2 rooms away). They are going to find it through dusting, etc. They must’ve always forgot. In regards to stealing, you have to remove valuables or take pictures of where they are & if they’re missing & you know the time frame, you’ll have to dismiss them. Without proof, they can cause you hassle so sometimes you have to attribute it to something else more tangible. Good luck.

I am with Burnt. I would go as far to say that they are only allowed in a certain part of the house. The living room, kitchen, clients bedroon (if needing to put client down for a nap) and bathroom. All other parts of the house are off limit. Get a small safe and put valuables in it hiding it in a room off limits. I live in a split and if I had needed to have a caregiver for Mom, there would be no reason for an aide to go anywhere passed the lower level where Moms bedroom/sitting area, bathroom and laundry room were. Next floor up was kitchen/dining area and living room. Next levels were bedrooms and another bath. No reason for an aide to go to those floors.

The problem we hear a lot is aides stealing. Food, paper products. One aide brought her children. Make sure you take an inventory. One poster did have things under lock and key but what she was leaving out seemed to be used up awfully fast. Making themselves something to eat is OK but trying to feed their family from the clients kitchen is not.

I posted a reply that seems to have disappeared. My single Aunt had an aide for years whom she loved. However, when she needed time off she left her daughter in charge and this daughter stole what wasn’t nailed down. She had my Aunt sign blank checks. We didn’t find out any of this until my Aunt had to go to a nursing home. The problem was her POA and only caregiver was my 95 year old father who visited when he could. All other relatives lived too far away to make regular visits and wouldn’t have known to look for checkbooks anyway. And what about those pizza orders for a hypertensive old woman? Sooo what do you think about geriatric care managers? How can you prevent an accomplished thief from wrapping a checkbook in clothing and taking it to a private space where cameras can’t see? How do you keep money around for food and other smaller expenses and not have it stolen? Cameras are good but not perfect. What cameras do you recommend? It is really terrible that people steal and scam the elderly!

You should be using either a trustworthy agency or dept, but you can also ask for verification the person DID pass a background check. You might be surprised how many "nice" agencies don't bother unless someone pushes as happened to us. Got the person's name? Snoop on line. Use every resource you can and see what you can dig up. In one case we had the aides name and she was introduced prior; during some small talk revealing a recent birthday...with that I was able to see what a horrible person she was as far as her driving record which the agency head had zero issues with though I did. WE did not proceed. You want to remove valuables and important papers anything with a signature. Inventory/take pictures of belongings. And most effective...I discovered by chance is a "safe" room. In our case, living with my folks my pup is a bit reactive and my parent's cannot handle her. So there is a residential locking handset on my bedroom door. So valuables and papers are kept safely locked up with a plausible excuse. OF course make sure there are no extra keys where your caree or the aide could find it. As a precaution we also got a knox box on loan from our city so all household related keys are locked in there in case of emergency. Or one to a trusted neighbor. BTW, really bad stuff involving the law will NOT typically be missed, but that doesn't mean minor stuff isn't of equal importance. And it's real easy to use the excuse of an older person's memory or dementia when something is missing. They can and will go through bedroom drawers when putting away laundry and find that special box with the pin worn only on Easter. Be safe, not sorry. We have a local agency that does BCI (state check) and FBI (national check). But don't underestimate the power of googling...our aide with multiple driving offenses was going to drive my mother. I would never get in a car with her. .....

We had 24/7 care at home for my dad starting 8 weeks after covid lockdown at his MC facility. I was around a lot checking on things & we went thru quite a few people who weren’t good fits for my dad and his needs. We lost clothing, jewelry n other valuables while he was in a facility. Nothing was lost while he was cared for at home- unless he misplaced it n then it was found again! I didn’t put in cameras b/c I thought that gave Dad no privacy, but in hindsight I wish I had. Everyone is one their A game with cameras. You’ll also see how your LO is behaving (or not) . You’ll know which stories to believe and can better plan for your LO b/c you’ll see the changes as they slowly happen. My two cents! Good luck and God bless

To Burntcaregiver...
I just saw your comment about my post.
I feel like you are putting the blame on me for the theft that occurred.
I did have most things locked in a safe. I had a few things in my bathroom so OK, I will take responsibility for that.
But the toilet paper, all the food and the damage (damage was clogged toilet because she flushed wipes that were clearly marked do not flush, she also flushed tampons, put a hole in my wall when she tripped over the vacuum cleaner hose and pushed the handle of my Husbands wheel chair through the wall) that she did most certainly I could not have prevented. How would she have fed my Husband if I locked the refrigerator and freezer? Who locks up toilet paper?
And why she would have taken a lip balm? (Odd thing about that I purchases several in a blister pack and wrote the flavor on the bottom, when the officer asked her to dump her purse one was in her purse)
My only caution about what happened to me is that you can not rely just on back ground checks.

So, I am 100% probably the most anal retentive person alive. I do lock up toilet paper. I have an Excel spreadsheet of food and other supplies such as cleaning, diapers, etc. My theft sheet is 67 pages long of stupid crap.

How do you know? You do not. With all this crime reform going on. Here in MI, as long as you do not kill someone, molest a child or do something with a life in prison sentence, you are automatically expunged after X years and the person never committed a crime, unless it is federal. You know fresh start and all.