diff --git a/SurveyLib.Core/Models/Completion.cs b/SurveyLib.Core/Models/Completion.cs
index 0ba6cf3..651440d 100644
--- a/SurveyLib.Core/Models/Completion.cs
+++ b/SurveyLib.Core/Models/Completion.cs
@@ -4,7 +4,9 @@ public class Completion
 {
     public int Id { get; set; }
     public int SurveyId { get; set; }
-    public DateTime FinishedAt { get; set; }
+    public DateTime FinishedAt { get; set; } = DateTime.UtcNow;
+
+    public int? CompletedBy { get; set; }
 
     public Survey Survey { get; set; }
     public ICollection<Answer> Answers { get; set; }
diff --git a/SurveyLib.Core/Repositories/IAnswerRepository.cs b/SurveyLib.Core/Repositories/IAnswerRepository.cs
index 59d2213..0906f21 100644
--- a/SurveyLib.Core/Repositories/IAnswerRepository.cs
+++ b/SurveyLib.Core/Repositories/IAnswerRepository.cs
@@ -5,4 +5,6 @@ namespace SurveyLib.Core.Repositories;
 public interface IAnswerRepository : IGenericRepository<Answer>
 {
     Task DeleteAsync(int questionId, int completionId);
+    Task<IEnumerable<Answer>> GetAnswersByCompletionIdAsync(int completionId);
+    Task<IEnumerable<Answer>> GetAnswersByQuestionIdAsync(int questionId);
 }
\ No newline at end of file
diff --git a/SurveyLib.Core/Repositories/ICompletionRepository.cs b/SurveyLib.Core/Repositories/ICompletionRepository.cs
index 9b41e97..b8cffac 100644
--- a/SurveyLib.Core/Repositories/ICompletionRepository.cs
+++ b/SurveyLib.Core/Repositories/ICompletionRepository.cs
@@ -4,5 +4,5 @@ namespace SurveyLib.Core.Repositories;
 
 public interface ICompletionRepository : IGenericRepository<Completion>
 {
-    
+    Task<IEnumerable<Completion>> GetCompletionsBySurveyIdAsync(int surveyId);
 }
\ No newline at end of file
diff --git a/SurveyLib.Core/Services/IAnswerService.cs b/SurveyLib.Core/Services/IAnswerService.cs
index d2122dc..2eb866d 100644
--- a/SurveyLib.Core/Services/IAnswerService.cs
+++ b/SurveyLib.Core/Services/IAnswerService.cs
@@ -4,9 +4,9 @@ namespace SurveyLib.Core.Services;
 
 public interface IAnswerService
 {
-    Task<bool> AddAnswerAsync(Answer answer);
-    Task<bool> UpdateAnswerAsync(Answer answer);
-    Task<bool> DeleteAnswerAsync(int id);
+    Task AddAnswerAsync(Answer answer);
+    Task UpdateAnswerAsync(Answer answer);
+    Task DeleteAnswerAsync(int id);
     Task<IEnumerable<Answer>> GetAnswersByCompletionIdAsync(int completionId);
     Task<IEnumerable<Answer>> GetAnswersByQuestionIdAsync(int questionId);
 }
\ No newline at end of file
diff --git a/SurveyLib.Core/Services/ICompletionService.cs b/SurveyLib.Core/Services/ICompletionService.cs
index 3a9430d..b6d4bab 100644
--- a/SurveyLib.Core/Services/ICompletionService.cs
+++ b/SurveyLib.Core/Services/ICompletionService.cs
@@ -4,8 +4,8 @@ namespace SurveyLib.Core.Services;
 
 public interface ICompletionService
 {
-    Task<bool> AddCompletionAsync(Completion completion);
-    Task<bool> UpdateCompletionAsync(Completion completion);
-    Task<bool> DeleteCompletionAsync(int id);
+    Task AddCompletionAsync(Completion completion);
+    Task UpdateCompletionAsync(Completion completion);
+    Task DeleteCompletionAsync(int id);
     Task<IEnumerable<Completion>> GetCompletionsBySurveyIdAsync(int surveyId);
 }
\ No newline at end of file
diff --git a/SurveyLib.Infrastructure.EFCore/Repositories/AnswerRepository.cs b/SurveyLib.Infrastructure.EFCore/Repositories/AnswerRepository.cs
index 4a84d49..88fbe40 100644
--- a/SurveyLib.Infrastructure.EFCore/Repositories/AnswerRepository.cs
+++ b/SurveyLib.Infrastructure.EFCore/Repositories/AnswerRepository.cs
@@ -47,4 +47,14 @@ public class AnswerRepository : IAnswerRepository
             .ExecuteDeleteAsync();
         await _context.SaveChangesAsync();
     }
+
+    public async Task<IEnumerable<Answer>> GetAnswersByCompletionIdAsync(int completionId)
+    {
+        return await _context.Answers.Where(a => a.CompletionId == completionId).ToListAsync();
+    }
+
+    public async Task<IEnumerable<Answer>> GetAnswersByQuestionIdAsync(int questionId)
+    {
+        return await _context.Answers.Where(a => a.QuestionId == questionId).ToListAsync();
+    }
 }
\ No newline at end of file
diff --git a/SurveyLib.Infrastructure.EFCore/Repositories/CompletionRepository.cs b/SurveyLib.Infrastructure.EFCore/Repositories/CompletionRepository.cs
index 5082e34..bc1c39c 100644
--- a/SurveyLib.Infrastructure.EFCore/Repositories/CompletionRepository.cs
+++ b/SurveyLib.Infrastructure.EFCore/Repositories/CompletionRepository.cs
@@ -41,4 +41,9 @@ public class CompletionRepository : ICompletionRepository
         await _context.Completions.Where(c => c.Id == id).ExecuteDeleteAsync();
         await _context.SaveChangesAsync();
     }
+
+    public async Task<IEnumerable<Completion>> GetCompletionsBySurveyIdAsync(int surveyId)
+    {
+        return await _context.Completions.Where(c => c.SurveyId == surveyId).ToListAsync();
+    }
 }
\ No newline at end of file