I'm at a loss as to how to deal with this. 

My siblings and I had to sell our mother's house when she was diagnosed with dementia about three years ago.  It was a group effort cleaning out her house.  All of us were not there at the same times. 

Several plastic bags of family photos going back decades were some of the items in the house.  Recently I started asking around for which sister has the photos.  There were some that were from my childhood and they meant a lot to me.  They don't matter to any of my sisters because I'm the oldest, and either they weren't born or were too young to know the childhood friends in the photos with me.

One sister told me that the sister I referred to in the subject heading--I'll call her Lizzie--was seen carrying the plastic bags of photos out of my mother's house.  When I asked Lizzie about them, she claimed that other sisters had them, and that she has no family photos.  Lizzie has a long history as the family klepto.  Many years ago she stole some belongings from my mother, and she threw them out into the trash to avoid being caught with them.  I learned years ago from other sisters never to lend any of my belongings to Lizzie because my sisters and my mother had lent things to her, and she never returned them.  I was once present when my mother confronted Lizzie about this, and she just sat snickering and laughing about it.  When she was in her early 20s she was caught shoplifting from a supermarket, and when they confronted her at the doors, she went into a furious assault against them, putting on an indignant, outraged act about "how dare" they accuse her.  She got away with it. 

About three weeks ago I sent around an email to all of my siblings--my sisters as well as my brothers.  One lives in northern California and the other lives in Florida.  I said that I was trying to find photos that mean a lot to me and that I was getting conflicting stories about who has the photos.  I mentioned hearing that Lizzie had carried bags full of the photos out of my mother's house.  She pulled the same tactic she used at the supermarket.  She answered in red text calling me "way out of line" and "paranoid" and said that whichever sister said she'd seen Lizzie carring the photos out of my mother's house was hallucinating.  I replied just by telling her that no, I am not out of line or paranoid.  Two other sisters said they would look for whatever photos they had in their homes and that I was welcome to check out what they had. 

Shortly before I sent this email, Lizzie had a high school graduation party at her home for her son at her home.  I noticed an old family photo album underneath one of her end tables.  I didn't say anything at the time because I didn't think it was the right time, at my nephew's graduation party.  I didn't want to risk a scene.  But I visited Lizzie's home two nights ago, and I noticed that the black photo album is no longer under the end table.  I'm sure she hid it because she didn't want to be caught lying about her having family photos. 

None of my sisters will come to my aid.  The sister who told me about seeing Lizzie with the bags of photos did not speak up when I sent my family email around to them all.  But they all know that Lizzie is capable of this and that she has the photos.  I'm in this completely on my own.  My brothers were living in distant states and weren't involved in cleaning out my mother's house, so they don't know enough about the situation to be much help.

The only language Lizzie understands is leverage and clout.  I have only one thing that might give me some leverage, but it doesn't come naturally to me to deal with people this way, so I'd like some advice.  I have a small B & W photo of my paternal grandmother, taken of her when she was two years old, in 1902 in England, where she was born.  As of now, none of my sisters know I have it, but I know that if they did know, they would want very much to have it scanned and to have me share that with them.  I can't use it as a bargaining chip until I've looked at all the photos my other sisters have.  I don't expect to find any of my childhood photos with them because I'm certain Lizzie has them stashed away.  But once I've done that, I'm considering sending my siblings an email telling them that I have this photo of my grandmother and telling them that no one is going to see it or gain any access to it until I am satisfied that I've found all of the childhood photos I want.  I'd tell them that I'm going to leave the bickering to them, that they can get together and go over the stories about who has which photos, and that it's up to them to make sure I get these photos, and to tell me who had them. 

What do people think of this?  Does anyone have any better ideas?  I am burning up with indignation and outrage and helplessness at her abusing me this way.  In the past I always protected myself from her klepto tendencies by never letting her get her hands on any of my belongings.  Now she has something that belongs to all of us, and it's no skin off of her nose to let me borrow the photos, scan them and put them in digital files, and return them.  I've never done anything to hurt her that would make me deserve this.  And her son, my nephew, also is an Aspie, and I don't want to jeopardize my relationship with him, which is special. 

Thanks for any advice anyone can offer.