Related Clues:

• 'I was volunteering at the orphanage at the time of the murder,' e.g.
• Criminal explanation
• Foundation, as of an argument
• Toddler's query
• Element of a murder mystery
• ''I ran out of gas,'' e.g.
• Reason to demonstrate
• Defendant's story
• Defendant's need
• The whales, say
• Story to verify
• Perp's excuse
• Motivational question?
• With 69-Across, optimistic question, or a possible title for this puzzle
• Suspect's "I was home all night," e.g.