Stolen NEM from android wallet

Guys I have been keeping a few thousands coins in Android wallet for about two months. I loged in today and found ZERO balance.The coins has been stolen. My transaction history shows that first 10 NEM was withdrawn and two minutes after whole balance!!! Could developers explain this???

It is mobile app for android.I never lost it and noone ever had access to wallet except me. Private key I keep in secure off line place and use strong password to log in. How someone can get access and withdraw funds???
This info I found in security section in the wallet.
Version:
1.0.66 BETA-Mainnet
Warning - this is development version and it can send to developers some sensitive information like transactions and/or encryption keys.
No private keys or passwords are being sent.

hmm…could you share the account address?

Does anyone of you have any experience with malicious software.Is it unnoticeable. I was online when coins was stolen.My device is protected. Allowing installation from unknown sorces was disabled . I did not installed any other apps for the last couple of weeks. How malicious software can get access to app protected with very strong password and the most disturbing why developers of this wallet do not respond to this issue. I posted it on many places.

Well either the private key or the password to the wallet was leaked, there is no other way to steal.

What could be a reason for "leaking"
We’ve already checked that .
https://bitcointalk.org/index.php?topic=654845.33480
Thank you anyway.

Hey @FindingNEMo next time I would suggest creating multisignature account, I made tutorial video about how to do it and what is the best available option to store your NEM securely: