If you feel like a loved one is lying about something, this no nonsense approach will get them to confess. In the least, it will confirm your suspiscions and help you figure a way forward.
Privacy and food
Go alone and take them food. Three is a crowd and will make them feel cornered. The food will make you instantly likeable.
Step in their shoes
Leave the accusatory tone outside. Talk directly and quietly while acknowleding their predicament.
Ask them to help you understand, suing sincerity and sympathy to communicate your concern for them.
Recognise their willingness to engage with you.
‘Thank you for accepting to see me. I appreciate it. Thing is, some of what you’re telling me isn’t adding up. Help me understand what I’m missing’.
Avoid questions
Maintain a monologue rather than asking them questions. This way you give the impression that you already know what is going on (or an idea at least).
Maintain the concern and genuine care even in this approach.
Communicate your understanding for the circumstances that led them to their mistake.
Think about short-term resolutions
Bring the consequences to short-term. They are likely to withhold the truth if they think the consequences are going to be far-reaching.
Avoid using those potential long-term consequences to threaten them.
Use language and statements that will give them some security and save them humiliation or embarrasment.
After that, give them space to come clean. Keep reassuring them that a confession is the beginning of fixing the issue.
Dominate the conversation
After creating a safe and understanding atmosphere for them to tell the truth, prevent them from taking control of the conversation.
Use commanding body language like holding up your hand when you want them to stop talking.
Use their first name and revert to your monologue. Maintain the impersonal aproach of wanting to find out what happened so that you can fix it together.
Remember, the guilty party needs to feel understood because only then can they feel that they have been forgiven.